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The crop rotation is a farm-scale management choice that dictates agronomic output, ecological impacts, and farm viability. Rotations have become less diverse recently. Re-diversifying may help agricultural systems meet the growing, dynamic demands from society and challenges from climate change. Using a long-term experiment, we tested whether diversified rotations could a) match the productivity (grain yield) of simplified rotations while b) stabilizing productivity against variable weather in the western U.S. Corn Belt. We identified rotation design choices that drive these productivity-stability dynamics. Although more productive rotations were more susceptible to weather (r = 0.63; p < 0.001), this tradeoff was surmountable (p < 0.001): the corn-oat-winter wheat-soybean (Zea mays L., Avena sativa L., Triticum aestivum L., Glycine max (L.) Merr.) rotation was a) no less productive than the highly unstable, corn-soybean rotation (p = 0.11); and b) only marginally less stable than the most stable rotation (p = 0.06). Crop selection and sequencing were critical to this outcome. High productivity was due to a) overyielding of individual crops in diversified rotations that increased with time; b) sequencing to allow higher-yielding winter crops; and c) beneficial crop legacy effects. Stability was highest in rotations that included crops belonging to more weather-niches (r 2 = 0.67; p < 0.001). Surprisingly, these weather-niches groups did not correspond to traditional categories like cool- vs warm-season crops. These results suggest four principles for the design, study, and implementation of diversified grain rotations that are stable under erratic weather and are as productive as current standard practices. • Long-term study of productivity and weather resistance in diversified grain rotations. • Most-productive 4-species rotation matched the locally common corn-soybean rotation. • Most-productive 4-species rotation was as stable as the most stable tested across weather patterns. • Selection and sequencing of crops for overyielding and weather complementarity are critical. • Principles for designing productive, reliable, diverse rotation are proposed. [ABSTRACT FROM AUTHOR]

At the agro-ecosystem scale, a combination of green manure and chemical nitrogen fertilizer improves crop yield but also exacerbates soil CO 2 emissions. However, it is unclear whether reducing nitrogen by reapplying green manure to fields can achieve high crop yields and improve carbon mitigation. This study aims to investigate the effects and underlying mechanisms of carbon emissions in maize fields under green manure reapplication combined with a reduction in nitrogen. A field experiment comprising five treatments (green manure reapplication combined with traditional nitrogen application (N100), green manure reapplication combined with a reduction in nitrogen of 10% (N90), green manure reapplication combined with a reduction in nitrogen of 20% (N80), green manure reapplication combined with a reduction in nitrogen of 30% (N70), and green manure reapplication combined with a reduction in nitrogen of 40% (N60)) was conducted at an arid oasis region in northwestern China from 2020 to 2022. This study investigated the effects of reducing nitrogen application while reapplying green manure to the field on maize grain yield, soil respiration rate, and carbon emission efficiency (CEE) and analyzed the relationship between soil respiration rate and soil temperature (Ts), soil water content (SWC), and crop biomass accumulation (BA). The N80 treatment significantly reduced soil carbon emissions (CE) but did not reduce maize grain yield, and it showed a significant increase in CEE of 7.7% compared with the N100 treatment. In addition, this system can ensure no reduction in net primary production (NPP), net ecosystem production (NEP), and carbon sequestration (CS) potential compared with N100 and significantly improves the NPP/CE value. Soil temperature and crop biomass significantly correlated with soil respiration, which explained 68.4–72.9% and 84.4–88.8% of the seasonal variation of soil respiration, respectively. However, there was no correlation between soil moisture and soil respiration. Therefore, reducing nitrogen application by 20% while multiple cropping with green manure application after wheat was a suitable nitrogen fertilizer management measure for improving carbon mitigation in arid areas without sacrificing maize yield. The results of this study provide valuable insights into long-term agricultural management strategies for achieving high agricultural production and environmental friendliness. • N80 ensured that maize grain yield does not decrease. • N80 reduced soil carbon emissions and improved carbon emission efficiency. • N80 ensured no reduction in NPP, NEP and Harvest-C. • N80 improved C sequestration and NPP/CE value. • Ts and BA are the main factors influencing carbon emissions. [ABSTRACT FROM AUTHOR]

How to plan crop planting under global warming is a key issue in the context of an emerging global food crisis. Although previous studies have utilized crop potential distribution for crop planting strategies, they overlooked the high and stable crop-yielding areas within the potential distribution zone, which hinders the optimal utilization of these areas. Taking China as a case, this study proposed a high and stable yield index based on crop potential yield using a hybrid model at site scale (i.e., establishing the relationship between the observed crop yield and the outputs of process-based LPJ-GUESS model as well as climate variables using the random forest method) and assessed planting suitability of China's main grain crops (i.e., maize, wheat, and rice) under future climate change using the index. According to the results, (1) the determination coefficients between observed and modeled yield in the hybrid models were 0.71, 0.49, and 0.66 for maize, wheat, and rice, respectively, suggesting that the hybrid model had an acceptable performance. Moreover, the hybrid models had much better performance than the LPJ-GUESS model in crop yield simulation at site scale. (2) Compared with the 2001–2020, future average potential yield of three crops in the actual cultivated land would decline in 2081–2100, where the declined areas for maize, wheat, and rice would account for 83.8–89.2 %, 68.2–70.2 %, and 74.2–80.9 % of cultivated land, respectively. (3) High yield and stable yield areas of each crop do not overlap completely spatially, indicating that establishment of the high and stable yield index for crop planting suitability measurement is necessary. Compared with the 2001–2020, the optimal suitability areas of each crop will decrease under future climate change, implying that future climate change will reduce and shift the high and stable yield area of each crop. (4) Spatial overlay between the actual distribution and the optimal suitability area of each crop demonstrates that the optimal suitability area of each crop has not and will not be occupied completely by actual crop planting, suggesting a large available area for the adjustment of future crop planting area. This work could facilitate spatial optimization of crop planting to adapt to future climate change in China. • A hybrid model was developed to estimate crop yield. • An index of high and stable yield for crop was established for crop planting. • Future climate will reduce potential yield and planting suitability of crops. • Optimal suitability area has not been completely occupied by actual crop planting. • Large space was detected for adjusting and newly developing crop planting. [ABSTRACT FROM AUTHOR]

Intercropping has gained widespread adoption among farmers due to its ability to yield higher outputs. The primary reasons behind the yield advantage of intercropping systems are the border effects. Among various factors influencing the inter-species relationship, nitrogen (N) plays a crucial role. However, yield and border effects of wheat/maize intercropping at different N levels have been poorly studied, especially under rainfed conditions with different rainfall year types. The objective of this study was to compare the contribution of different crop strips to yield at different N levels and to explore the impact of different precipitation on crop physiological characteristics and water use of intercropping systems in rainfed areas. A field experiment was conducted between 2019 and 2021 in Yangling, Shaanxi Province, adopting a two-factor design, with the main treatment as planting pattern (sole wheat; sole maize; wheat/maize intercropping), and the secondary treatment as three N levels (0, 180, 300 kg ha−1 for wheat and 0, 235, 360 kg ha−1 for maize). Results showed that, intercropping increased total yield and land productivity, with a land equivalent ratio of 1.05–1.15. The intercropping system led to increased water consumption during crop growth, however, it also exhibited a notable improvement in water use efficiency, with a 5.2–16.9% increase compared to sole wheat cultivation. During the symbiotic period, intercropping wheat showed competitive advantages, resulting in yield increments of 16.4–31.2% over the two-year period. Border row wheat contributed 63.7% of the total production, with the increase in yield mainly attributed to an increase in the number of spikes and 1000-kernel weight. On the other hand, the intercropping maize showed a competitive disadvantage during the symbiotic period. The leaf area index, net photosynthetic rate, and yield of border row maize were comparatively lower than those of inner maize. However, no significant differences were observed between the yield of inner row maize and that of sole maize. After the wheat harvest, the intercropping maize resumed growth. The growth of intercropping maize was constrained by N and moisture conditions. In 2020 (Precipitation: 572.8 mm), the yield of intercropping maize increased by 3.2% compared to sole maize under N2 treatment, but in 2021 (Precipitation: 251.4 mm), the yield of intercropping maize decreased by 1.1%− 4.3%. Wheat/maize intercropping has clear advantages in land use in the Northwest China due to the availability of more resources for wheat/maize intercropping, especially in the border rows of wheat. The recovery of late-sown crops is limited by water and nitrogen, and increasing the water and nitrogen supply of late-sown crops can better play the advantages of intercropping. This study demonstrates that the contribution of intercropping system component crops to yield, and provides practical guidance for improving the productivity of wheat/maize intercropping systems in Northwest China. • The border effects of wheat/maize strip intercropping were studied. • Border wheat rows received better light, nutrition and moisture conditions. • The border wheat contributed 63.7% of the total wheat output. • The recovery growth of maize was affected by nitrogen and precipitation. • Wheat/maize intercropping improved land productivity in Northwest China. [ABSTRACT FROM AUTHOR]

As maize-based crop rotation systems are essential to ensure global food security, understanding the effect of the preceding crops and the associated management on the subsequent maize is crucial. Here we address this view with a 6-year field experiment in the North China Plain's annual winter wheat and summer maize rotation system. Effects of preceding wheat with three water management (conventional irrigation, Con.W/M; optimized irrigation, Opt.W/M; minimum irrigation, Min.W/M) on maize yield and water consumption are investigated. We find that water management in the preceding wheat crop does not affect the subsequent maize yield but increases the interannual yield variability. Over the six years, an average yield of > 10.7 Mg ha-1 is achieved for maize in the three treatments. The highest coefficient of variation (CV) of yield is observed in Min.W/M (12.0%), while there is no significant difference in CV between Con.W/M and Opt.W/M. The annual water consumption follows a decreasing trend in the order of Con.W/M (357 mm), Opt.W/M (332 mm), and Min.W/M (290 mm), which primarily attribute to variations in initial water storage in the deeper soil profile (below 80 cm). The variation in water storage would be eliminated during the following maize growing stages due to ample rainfall in the temperate continental monsoon climate. The findings show that kernel weight (KW) is the primary determinant (accounting for 55–86%) to the observed variations in maize yield. In the Min.W/M treatment, the interactive effect of killing degree days, growing degree days, maximum temperature, and solar radiation accounts for 85% of the variation observed in KW. This study provides insights into the effect of the preceding wheat on the subsequent maize for grain yield and water consumption in the rotation system. • Analyzed wheat irrigation impact on subsequent maize's water use and yield. • Water management in wheat doesn't affect maize yield but raised yield variability. • The highest CV of maize yield is observed in Min.W/M treatment. • Yield variability is mainly from kernel weight in Min.W/M treatment. [ABSTRACT FROM AUTHOR]

• Maize and wheat are proposed for diversification, but irrigation advice is limited. • Soil moisture content was above or near drained upper limit for depths below 0.5 m. • A significant effect of irrigation on yield was observed for maize only, in one year. • One irrigation, in addition to a starter irrigation, generally is sufficient to grow a crop. • Low-input maize cultivation is not always profitable and low fertilizer rates increase risk of negative returns. Further efforts are needed to combat poverty and agricultural productivity problems in the delta region of Bangladesh. Sustainable intensification of crop production through irrigation and production of cash crops such as maize and wheat might be a promising option to increase income and diversify food production. Only limited research has however been conducted on the potential of using surface water from canals as an irrigation source for maize and wheat production in the delta region. To better understand the contribution of shallow groundwater to crop production and number of irrigations needed for maize and wheat in this unique coastal environment, we conducted multi-locational trials on farmers' fields over three rabi seasons. In addition to soil moisture and salinity, we recorded the depth and salinity of the shallow water table throughout these experiments. Maize in particular requires considerable capital investment for seeds, fertilizer, irrigation and labor. Although farmers express wide interest in maize – which can be sold as a profitable cash crop into Bangladesh's expanding poultry feed industry – many of them are reluctant to invest in fertilizer because of the high entry costs. We therefore also investigated the profitability of growing maize under low and high (recommended) fertilizer regimens. Volumetric soil moisture at sowing and during the grain filling phase or at maturity indicated that there is ample supply of water in the profile. Most measurements were above the drained upper limit (DUL). We attributed this to the generally shallow water table depths, which never exceeded 2.75 m at any location, but generally stayed between 1–2 m depth throughout the season. The region's soil texture classes (clay loams, silt loams and silty clay loams) are all conducive for capillary rise of water into the rooting zone. Consequently, irrigation had a significant effect on maize yield in the driest winter only, whereas for wheat, it had no effect. The key for a successful maize and wheat production in the delta region of Bangladesh is to ensure a good crop establishment, which can be achieved with a starter and an additional irrigation at crown root initiation for wheat and at V6-8 for maize. Maize however is not always profitable. Compared to low fertilizer rates, higher rates reduced losses in low yielding site-years and increased profits in high-yielding site years. This indicates that it is advisable for farmers not to reduce fertilizer rates. Low-risk financial credit with rationally structured interest rates that allow farmers to invest in maize could potentially offset these constraints. [ABSTRACT FROM AUTHOR]

Highlights • Ecological intensification management (EI) was compared with average farmer practice (FP). • We evaluated resource productivity and its components at the crop sequence level. • Water and radiation productivities were higher in EI than in FP. • Resource use efficiencies increased more than resource capture in EI as compared with FP. • The EI management reduced partial factor productivity of applied N but improved the partial N balance. Abstract The challenge to increase agricultural production with a minimum environmental impact requires to reach the maximum efficiency in the capture and use of resources such as photosynthetically active radiation (PAR), water, and nitrogen (N). Such requisites are encompassed in the ecological intensification (EI) concept. The aims of this work were to evaluate at a crop sequence level: i) crops yields, ii) water and radiation productivity and its components, i.e. resource capture and resource use efficiency, and iii) partial factor productivity of applied N (PFPN), partial nutrient balance for N (PNB), N uptake and N utilization efficiency of a two-year, three-crop sequence (wheat [ Triticum aestivum L.]/soybean [ Glycine max (L.) Merr.] double crop – maize [ Zea mays L.]) carried-out under EI principles in comparison with the same crop sequence under current farmer practices (FP) in two contrasting locations of the Argentinean Pampas, i.e. Paraná (-31°50′; -60°31′) at the northern Pampas and Balcarce (-37°45′, -58°18′) at the southern Pampas. Experiments were carried-out during four consecutive years, covering two complete cycles of the crop sequence. For the accumulated grain production of the crop sequence, EI management outyielded FP from 13 to 42%, depending on environmental conditions. Maize yield accounted for most of the variation (41–64%) of the accumulated grain yield of crop sequence, whether in EI as in FP. Average grain yield differences between EI and FP treatments were 274 g m−2 for maize, 69 g m−2 for wheat and -2 g m−2 for soybean. Water and radiation productivities of the sequence were higher in EI than in FP (26% for water and 17% for radiation; P < 0.0001), mainly because of increases in resource use efficiencies. EI reduced partial factor productivity of applied N, but improved partial nutrient balance for N as compared with FP. These reductions in partial factor productivity of applied N were less than proportional than the increases in N rate. Moreover, in spite of the higher N rate in EI respect to FP, N utilization efficiency (N ut E), i.e. grain per unit N uptake, was higher across all situations in EI. Our results showed that the challenge to obtain high grain yields by increasing N rate in a medium-input system could be achieved even with an increase in N ut E. Grain yields improvements, and increases in radiation and water productivity were reached by applying a set of agronomic practices that included improved genetics, crop and fertilizer N management englobed under EI concept. [ABSTRACT FROM AUTHOR]

Winter wheat ( Triticum aestivum L.)-fallow (WF) remains a prominent cropping system throughout the Central Great Plains despite documentation confirming the inefficiency of precipitation storage during the summer fallow period. Wheat yield is greatly influenced by available soil water at planting, and that quantity is influenced by cropping intensity, tillage intensity, crop grown prior to winter wheat planting, and length of the non-crop period prior to winter wheat planting. The objective of this study was to determine the effect of cropping system intensity, tillage, and crop prior to wheat planting on available soil water at planting and the probabilities of having certain minimum amounts of available soil water at wheat planting. Available soil water was measured at wheat planting for nine cropping systems varying in fallow frequency, tillage intensity, and crop prior to wheat over a 25-yr period at Akron, CO. Available soil water at wheat planting was found to be greatest (average 218 mm) for no-tillage (NT) and reduced-tillage (RT) systems in which a fallow period of 12–14 months preceded wheat planting. The lowest amounts of available soil water at wheat planting were found for the continuously cropped rotations (average 100 mm). The cumulative probability exceedance graphs of available soil water at planting fell into three groupings: 1) the five rotations that had a NT or RT fallow period prior to the next wheat crop; 2) the WF (conventional till) rotation; 3) the three rotations with either pea ( Pisum sativum L.) or proso millet ( Panicum miliaceum L.) prior to the next wheat crop. These graphs provide a valuable decision support tool for helping farmers assess risk in moving from a WF cropping system to a system of greater cropping intensity and diversity. [ABSTRACT FROM AUTHOR]

The Indo-Gangetic Plains (IGP) of India is dominated with rice − wheat cropping system that occupies almost 10.5 million ha area. The sustainability of rice-wheat system is under threat due to numerous water-, nutrients-, weeds- and environment-related problems, mainly, due to the cultivation of rice. Suitable crop and soil management practices with a bias to conservation agriculture (CA) that can sustain soil and environmental health as well as improve crop and water productivity, are required for the Indian IGP. Maize can be a viable alternative to rice and a potential driver for diversification of rice-wheat system. The acreage of maize is on the increase in conventional and conservation agriculture-based cereal systems of India in recent years. Therefore, a field experiment, involving a maize ( Zea mays L.)-wheat cropping system was undertaken on a sandy clay loam soil for three years (2010–11 to 2012-13) in New Delhi to evaluate the impacts of CA on crop and water productivity, profitability and soil organic carbon (SOC) accumulation. There were five CA-based treatments in first year, and two treatments were introduced in second year (2011-12) onwards. The experiment was laid out in a randomized complete block design with three replications. In all the residue retention plots, wheat residue was retained in maize crop and maize residue was retained in wheat crop under zero till conditions. Results showed that the plots under permanent broad bed with residue (PBB + R) and without residue (PBB) resulted in ∼29 and ∼26% higher maize grain yield, respectively than conventional tillage (CT) (2.6 t ha −1 ), but wheat grain yields were comparable in all the treatments in first year. Maize grain yield in second year under PBB + R and zero tillage with residue (ZT + R) were 55 and 43% higher than CT plots (2.8 t ha −1 ). Three-year mean maize yields due to PBB + R and permanent narrow bed with residue (PNB + R) were 28 and 15% higher than that in CT plots (3.3 t ha −1 ). The PBB + R resulted in 11% higher two-year mean water productivity in maize than PBB (∼without residue), but both these treatments were comparable in this regard in wheat. The ZT + R plots resulted in 14% and 22% higher two-year mean water productivity, respectively in maize and wheat than ZT plots. Overall, the plots under PBB + R had 57% and 19% higher mean water productivities in maize and wheat, respectively compared with CT plots. Again, the PBB + R plots gave 12% higher two-year mean net returns compared with CT plots. With regard to net returns, the plots under permanent narrow bed with and without residue (PNB + R; PNB) were inferior to PBB, PBB + R, ZT and ZT + R plots. Retention of both-season crop residues could significantly improve SOC concentration in surface (0–5 cm) soil. The PBB + R resulted in highest SOC pool at 0–30 cm soil layer, which was significantly higher than that in CT. This system showed maximum carbon sequestration potential. Thus, this CA practice, which involves PBB + R is superior to other practice. This would save water through higher water-use efficiency, and lead to accumulation of more carbon in soil with higher sequestration potential, besides giving sustainable production through maize-wheat system over the years. This can be adopted across the IGP regions of India, where irrigated rice-wheat system is in practice, and in similar agro-ecologies of the tropics and sub-tropics under irrigated conditions. [ABSTRACT FROM AUTHOR]

Development of semi-dwarf wheat (Triticum aestivum) and rice (Oryza sativa) led to increased yields and agronomic efficiencies with less lodging. While these short-stature cereals have become common in global crop production, commercial maize (Zea mays L.) hybrids remain tall. There is no information currently available on plant N uptake or yield responses to N timing for short stature maize hybrids. We tested three hypotheses on short-stature and tall maize hybrids 1) short-stature maize hybrids would have similar yield response to in-season N application compared to tall hybrids, 2) short-stature maize hybrids would have similar dry matter and N uptake patterns to tall hybrids, and 3) there would be significant partitioning differences between short-stature and tall hybrids in dry matter and N within the plants at multiple growth stages. In ten side-by-side field trials across eight site-years in the Midwestern USA, we tested the yield response and underlying nitrogen physiology of short-stature maize hybrids and tall comparators to split-rate N application. We show that split-rate application of 50% of the total N at mid-vegetative stages (V6) averaged 0.24 t ha−1 more grain yield across 10 field trials (positive yield response in 6 out of 10 trials) compared to a single 100% up-front N application, with the same pattern for short-stature and tall hybrids. In both hybrid statures, V6 N applications showed more frequent improvement in grain yield than V12 N applications. Total N uptake at maturity was not different between short-stature hybrids and their tall counterparts (p = 0.62). N partitioning differed between short-stature and tall hybrids; leaves in short-stature hybrids had 5% higher N concentration and 13% more N content in early vegetative development, stalks had 18–27% less dry matter and 5–25% less N content, depending on growth stage, while R1 ears averaged 18% more dry matter and N accumulation (p < 0.10 in all cases). At maturity short-stature hybrids had 4% higher harvest index and 3% higher N harvest index (p < 0.10). Based on these results, we expect that N management recommendations in short-stature maize hybrids would be similar to their tall counterparts, but that short stature mitigates logistical risk by providing more flexibility for in-season N applications. This study provides a unique, robust dataset on yield and physiological response to split-rate N treatments in commercially relevant maize hybrids. • Short stature in maize simplifies in-season N application and later crop management. • Split-rate N applications at V6 increased hybrid yields 60% of the time, with similar patterns for short-stature and tall hybrids. • Overall, short-stature maize yielded similarly to tall comparators. • Short stature led to greater partitioning of N and dry matter to the grain than tall hybrids. • Greater flexibility for in-season N fertilization in short-stature maize reduces in-season application risks. [ABSTRACT FROM AUTHOR]

Soil CO 2 emissions respond differently to different tillage practices. However, limited information is available regarding the impact of conventional tillage (CT) and no-tillage (NT) on soil CO 2 emissions and the primary controlling factors or processes. The goal of this study is to derive the relationship of soil CO 2 emissions with soil physicochemical properties from differently tilled soils in a typical winter wheat summer maize rotation system. We hypothesized that soil tillage practices would impact the soil carbon cycle by modifying soil physical and chemical properties, which would in turn affect the soil CO 2 emissions. The study was conducted from 2018 to 2022 with two tillage practices using a randomized complete block design with three replicates. A leading international real-time monitoring system in situ was used to collect soil CO 2 emission data. Cumulative soil CO 2 emissions were reduced by 28.7% in maize and increased by 9.0% in wheat under NT as compared to CT. On an annual scale, the cumulative CO 2 emissions were decreased by 20.5% in NT as compared to CT. Maize season accounted for 70% 78% of soil CO 2 emissions. NT improved the aboveground biomass by 7.74% and 6.44%, and grain yields by 10.2% and 4.49% for maize and wheat, respectively. The soil CO 2 emission intensity of maize was reduced by 35.9% under NT as compared to CT. No significant differences were discovered under the two tillage practices for soil CO 2 emission intensity of wheat. For maize, NT increased the bulk density, subsequently decreasing soil temperature and increasing soil moisture. NT also led to higher soil organic carbon and total nitrogen content, ultimately resulting in a significant reduction in soil CO 2 emissions. For wheat, NT increased soil bulk density, further increasing soil moisture and lowering soil pH. NT thus resulted in lower soil organic carbon and total nitrogen content, ultimately leading to enhanced soil CO 2 emissions. Some of these observations might not be consistent with theoretical predictions, which indicated that the unconsidered factors of actual field conditions might have much significant effects. Overall, NT can be extensively used as an eco-friendly cropland tillage practice based on its positive effects of reducing CO 2 emissions and increasing crop yields. [Display omitted] • CO 2 emission variations by tillage were evaluated by the structural equation model. • No-tillage (NT) decreased CO 2 emissions by 28.7% in maize and increased by 8.99% in wheat. • Annual CO 2 emissions were decreased by 20.5% under NT than conventional tillage (CT). • Maize season accounted for 70% 78% of soil CO 2 emissions. • CO 2 emission intensity of maize was reduced by 35.9% under NT compared with CT. [ABSTRACT FROM AUTHOR]

A common dryland rotational cropping system in the semi-arid central Great Plains of the USA is wheat ( Triticum aestivum L.)-corn ( Zea mays L.)-fallow (WCF). However, the 12-month fallow period following corn production has been shown to be relatively inefficient in storing precipitation during the summer months and in some years could leave the soil vulnerable to wind erosion. The objective of this experiment was to determine the effect on system productivity when the fallow period in a WCF rotation was replaced with spring-planted forage triticale ( X Triticosecale rimpaui Wittm.). The 3-yr study was conducted at Akron, CO and Sidney, NE under both dryland and very limited irrigation conditions (to approximate average precipitation during the growing season). Growing season precipitation during the course of the study was above-average in five of the six site-years. Over a wide range of wheat water use (361–591 mm) wheat yields ranged from 1696 kg ha −1 to 5527 kg ha −1 . Wheat yields averaged 17% lower when triticale (T) replaced fallow, primarily because of reductions in water content at wheat planting. Corn yields were unaffected by triticale replacing fallow and ranged from 3159 kg ha −1 to 8085 kg ha −1 . Triticale yields ranged from 2967 kg ha −1 to 6724 kg ha −1 . System productivity as quantified by system net returns was greater for WCT than for WCF when growing season precipitation was above-average resulting in triticale production over 6000 kg ha −1 , but even in drier years net income was not reduced when the fallow phase was replaced with triticale production. A WCT rotation can be recommended over WCF provided that growing season precipitation is not far below average and there is an available market for the triticale forage produced. Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture. The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where applicable, sex, marital status, familial status, parental status, religion, sexual orientation, genetic information, political beliefs, reprisal, or because all or part of an individual's income is derived from any public assistance program. (Not all prohibited bases apply to all programs.) Persons with disabilities who require alternative means for communication of program information (Braille, large print, audiotape, etc.) should contact USDA's TARGET Center at (202) 720-2600 (voice and TDD). To file a complaint of discrimination, write to USDA, Director, Office of Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250-9410, or call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal opportunity provider and employer. [ABSTRACT FROM AUTHOR]

Intensive rice (Oryza sativa)-based cropping systems in south Asia provide much of the calorie and protein requirements of low to middle-income rural and urban populations. Intensive tillage practices demand more resources, damage soil quality, and reduce crop yields and profit margins. Crop diversification along with conservation agriculture (CA)-based management practices may reduce external input use, improve resource-use efficiency, and increase the productivity and profitability of intensive cropping systems. A field study was conducted on loamy soil in a sub-tropical climate in northern Bangladesh to evaluate the effects of three tillage options and six rice-based cropping sequences on grain, calorie, and protein yields and gross margins (GM) for different crops and cropping sequences. The three tillage options were: (1) conservation agriculture (CA) with all crops in sequences untilled, (2) alternating tillage (AT) with the monsoon season rice crop tilled but winter season crops untilled, and (3) conventional tillage (CT) with all crops in sequences tilled. The six cropping sequences were: rice-rice (R-R), rice-mung bean (Vigna radiata) (R-MB), rice-wheat (Triticum aestivum) (R-W), rice-maize (Zea mays) (R-M), rice-wheat-mung bean (R-W-MB), and rice-maize-mung bean (R-M-MB). Over three years of experimentation, the average monsoon rice yield was 8% lower for CA than CT, but the average winter crops yield was 13% higher for CA than CT. Systems rice equivalent yield (SREY) and systems calorie and protein yields were about 5%, 3% and 6%, respectively, higher under CA than CT; additionally, AT added approximately 1% more to these benefits. The systems productivity gain under CA and AT resulted in higher GM by 16% while reducing the labor and total production cost under CA than CT. The R-M rotation had higher SREY, calorie, protein yields, and GM by 24%, 26%, 66%, and 148%, respectively, than the predominantly practiced R-R rotation. The R-W-MB rotation had the highest SREY (30%) and second highest (118%) GM. Considering the combined effect of tillage and cropping system, CA with R-M rotation showed superior performance in terms of SREY, protein yield, and GM. The distribution of labor use and GM across rotations was grouped into four categories: R-W in low-low (low labor use and low GM), R-M in low-high (low labor use and high GM), R-W-MB and R-M-MB in high-high (high labor use and high GM) and R-R and R-MB in high-low (high labor use and low GM). In conclusion, CA performed better than CT in different winter crops and cropping systems but not in monsoon rice. Our results demonstrate the multiple benefits of partial and full CA-based tillage practices employed with appropriate crop diversification to achieve sustainable food security with greater calorie and protein intake while maximizing farm profitability of intensive rice-based rotational systems. • Rice-maize (R-M) outperformed over all other rice-based cropping systems considering yields and profits. • Conservation agriculture (CA) and alternate tillage (AT) outperformed than conventional tillage (CT). • R-M and rice-wheat-mungbean systems are more beneficial when layered with CA and AT. • Rice-rice system is more labor intensive and less profitable than other systems. • CA is good for winter crops and for cropping systems but not for rice but AT can be viable alternative option. [ABSTRACT FROM AUTHOR]

Combinability of species in intercrops depends on the production conditions and there is limited information on the potential of intercropping under conventional (i.e., non-organic) management in Western Europe. Here we determined productivity of four crop species (maize, Zea mays L.; wheat, Triticum aestivum L.; faba bean, Vicia faba L.; pea, Pisum sativum L.) in six different bi-specific mixture compositions. Species were spring-sown and fertilized in their strips according to common practice for monocrops. Strips were 1.5 m wide enabling strong interspecific interactions. Intercrops with maize, a species sown and harvested later than the other three species, had land equivalent ratio (LER) values that were in four out of six cases significantly greater than one, from 1.14 ± 0.04 to 1.22 ± 0.05 in 2018, and from 0.98 ± 0.06 to 1.15 ± 0.01 in 2019. Simultaneous intercrops comprising two of the other three species had LER values that tended to be lower than one, even though many LERs were not significantly different from one: from 0.94 ± 0.02 to 0.95 ± 0.04 in 2018, and from 0.80 ± 0.08 to 0.93 ± 0.04 in 2019. The yield gain (net intercropping effect; NE) in relay intercrops with maize ranged from 1.33 ± 0.59 to 2.01 ± 0.54 Mg ha−1 in 2018, and from 0.29 ± 0.41 to 1.04 ± 0.14 Mg ha−1 in 2019. The NE of simultaneous intercrops ranged from −0.43 ± 0.13 to −0.27 ± 0.22 Mg ha−1 in 2018, and from −1.17 ± 0.49 to −0.36 ± 0.22 Mg ha−1 in 2019. Results indicate that temporal complementarity between species drove the LER (or NE) in these experiments. On the other hand, values of the LER (or NE) were similar in species combinations with or without legumes, suggesting no major role for complementarity for nitrogen capture under the conditions of the study. Faba bean was the most competitive species and reached high partial LER and NE values in intercrops at the expense of the companion species. Competition from faba bean reduced the grain yield of wheat and pea more than it increased faba bean grain yield, resulting in negative net effects. Results suggest that relay strip intercropping can improve land use efficiency and total grain yield in conventional farming in Western Europe if species have temporal complementarity. • We combined maize, wheat, faba bean and pea as bi-specific intercrops. • Yield advantage was found if species exhibited temporal complementarity. • Highest LER was obtained in relay intercropping with species competing strongly for resources. • Nitrogen capture complementarity was not influential. • Border rows of strips were affected the most by intercropping. [ABSTRACT FROM AUTHOR]

Yield-scaled nitrous oxide (N 2 O) emission (YSNE) has been recognized as a means for developing appropriate nitrogen (N) management strategies to balance food security and mitigating N 2 O emissions. To better understand and use the concept of YSNE, it is essential to be assessed under various field conditions. The main objectives of this study were to assess the relationship between N inputs and YSNE with published results and identify response patterns of YSNE to N inputs. We assessed the relationship between N inputs and YSNE using published results encompassing 1800 observations (published from 1980 to 2020) from maize, rice, and wheat crops worldwide. Background yield-scaled N 2 O emission (BYSNE; a YSNE in the condition of zero N input) was significantly different by crop type. Rice (90.8 ± 12.9 g N 2 O−N Mg−1) had lower BYSNE compared to maize (174.2 ± 30.1 g N 2 O−N Mg−1) and wheat (325.4 ± 41.8 g N 2 O−N Mg−1). BYSNE was positively correlated with annual mean temperature in maize, rice, and wheat fields. BYSNE was negatively correlated with soil total nitrogen contents in rice fields. Over 60% data set showed a positive relationship between N inputs and YSNE in all three crops studied. A small proportion of the dataset had an optimum N rate that minimized YSNE. The results suggest that in general, lower N input rates result in lower YSNE in crop production. YSNE can be reduced in three ways: increasing yields (Type 1), reducing N 2 O emissions (Type 2), and both increasing yields and reducing N 2 O emissions (Type 3). To identify appropriate measures, we suggest a N 2 O emission-yield curve combining responses of yields and N 2 O emissions to N inputs. In type 1, 2, and 3 measures, an N 2 O emission-yield curve is shifted to the right, down, and both right and down, respectively. Through identifying direction and magnitude of the shifting, the effects of applied measures on yields and N 2 O emission in N input levels can be easily compared and recognized. This study provided insights into the nature of YSNE and how YSNE responds to N inputs. It also suggested an N 2 O emission-yield curve, which can be useful to identify how certain measures affect both N 2 O emissions and crop yields. The information can be useful for scientific community and policymakers developing appropriate N management strategies to balance food security and the mitigation of N 2 O emissions. [Display omitted] • Background yield-scaled N 2 O emission (BYSNE) varied by crop type. • BYSNE was positively correlated with annual mean temperature. • Over 60% data sets showed consistently lower yield-scaled N 2 O emission as N input decreased. • N 2 O emission yield curve showed the effects of mitigation measures on both yields and N 2 O emission. [ABSTRACT FROM AUTHOR]

The observed historical changes in crop phenological events are not only as a sensitive indicator to temperature variations but also the consequence of agronomic management such as adjustment of sowing date, cultivar selection and innovative farming practices. Clarifying how these factors influence crop phenology is of paramount importance in understanding/implementing adaptation strategies to future climate change. Changes in phenophases of dryland spring-sown wheat and maize were investigated using the observed phenological data from 1992 to 2013 across the Loess Plateau. Using a series of phenological growth models, we illustrated that once the varietal effect was fixed, rising temperature alone produced a general advancement on dates of heading and maturity, leading to a significant shortening of the vegetative phase (5.2 days decade −1 in wheat and 1.1 days decade −1 in maize), a shortened duration of reproductive phase (0.9 and 2.0 days decade −1 respectively) and the length of whole growing season (6.1 days decade −1 in wheat and 3.0 days decade −1 in maize). In contrast, cultivar shifts prolonged the reproductive duration and the growing season length by 2.2 and 4.7 days decade −1 for spring wheat, and 3.3 and 1.5 days decade −1 for maize, respectively. The continuous update of cultivars during the past two decades has offset 63.5% of the shortening effect of growing season length caused by rising temperature for both crops. Our data indicate that adjusting sowing date and shifts to longer season cultivars are the critical adaptive strategies to cope with temperature increases in dryland spring-sown wheat and maize in the Loess Plateau or regions with similar environments. [ABSTRACT FROM AUTHOR]

Estimating plant nitrogen concentrations (PNCs) with remote sensing technology is critical for ensuring precise field nitrogen (N) management. Compared with other remote sensing platforms, low-altitude unmanned aerial vehicles (UAVs) produce images with high spatial resolutions that can be used to clearly identify soil and vegetation. Previously, many spectral indices were designed to remove soil effects to obtain optimal PNC predictions. Herein, we attempt to enhance the PNC prediction accuracy only by removing soil pixels in high-resolution images. Thus, we aimed to collect a dataset containing different crops and image types to investigate whether removing soil pixels to purify crop spectra can improve PNC estimations. For this purpose, N fertilizer experiments were conducted on cotton (Gossypium hirsutum L.), wheat (Triticum aestivum L.) and maize (Zea mays L.), and multispectral and hyperspectral UAV images and PNCs were collected at different growth stages. The multispectral images had actual high spatial resolutions, while the hyperspectral images had virtual high spatial resolutions constructed by fusing high resolution panchromatic images and coarse resolution hyperspectral images. These images represent two typical UAV image types. First, for each crop, the relative changes and driving forces associated with the purified and nonpurified spectra were analyzed under different growth stage, N treatment. Then, three commonly used methods, the spectral index (SI), partial least squares regression (PLSR) and artificial neural network (ANN) methods were used to design PNC prediction model using purified and nonpurified spectra respectively. The results showed the differences between purified and nonpurified spectra were affected by the proportion of crop pixel, sunlit soil pixel and sunshade soil pixel in image. This influence had various trends and magnitudes among different N treatment, growth stages and crop types. It is better to remove soil pixels in imagery, when designing PNC prediction model for plants across growth stages, crop types or even in a single growth stage. The results from actual high spatial resolution images demonstrated this point, with the best PNC prediction model from purified spectra. When considering virtual high spatial resolution image, as the spectrum obtained for each vegetation pixel still represented a mixed vegetation and soil spectrum, removing soil pixels showed no improved performance for PNC estimation. These results provide a reference for others to reasonably choose an optimal data-processing method for constructing PNC prediction models. • Plant nitrogen concentration can be estimated using UAV-based images. • Purified and nonpurified spectra exist significant difference. • Plant nitrogen concentration can be better estimated using purified spectra. [ABSTRACT FROM AUTHOR]

This study aimed to identify whether nitrogen (N) use efficiency in a summer-maize/winter-wheat double-cropping system of the North China Plain (NCP) could be increased by adjusting N supply to crop N demand, and through the use of alternate N fertilizers and application strategies. In a static experiment conducted on a farmers’ field six reduced N treatments were compared to farmers’ practice (FP: 550 kg (N) ha −1 a −1 ) and a control treatment (CK). With few exceptions of single treatments in single cropping-seasons, the optimized fertilization of N did not lead to a yield reduction of either summer-maize or winter-wheat. The grain yield of summer-maize ranged between 5.8 and 7.1 Mg ha −1 . The grain yield of wheat ranged between 4.4 and 6.2 Mg ha −1 . For the first two vegetation periods of summer-maize, the recovery efficiency (RE N : 0.09–0.30 kg kg −1 ) and agronomic efficiency of N (AE N ) were mainly affected by the yield achieved in the control treatment (5.7 and 5.9 Mg ha −1 ), which was not significantly reduced compared to most fertilized treatments. In the third vegetation period of summer-maize, an increase of RE N of the reduced treatments (0.37–0.58 kg kg −1 ) was determined compared to FP (0.21 kg kg −1 ). In both vegetation periods of wheat RE N of the reduced treatments (0.34–1.0 kg kg −1 ) was significantly higher compared to FP (0.26 and 0.27 kg kg −1 ). The highest cumulated AE N , as well as cumulated grain yields were observed when ammonium sulphate nitrate + 3,4-dimethylpyrazolephosphate (ASN DMPP ) was applied according to crop N demand and residual soil mineral N. The highest RE N was observed when urea ammonium nitrate was applied in a shallow, banded depot (UAN DEP ). This research demonstrates that N application rates in a maize/wheat double cropping system may be significantly reduced compared to common farmers’ practice, without negatively affecting grain yield, thereby increasing N use efficiency. [ABSTRACT FROM AUTHOR]

Highlights: [•] Integrated NPK plus manure fertilization increases SOC and soil total N. [•] The application of phosphorus (P) with NK maintains SOC in maize–soybean–wheat rainfed cropping systems. [•] The application of NPK plus manure fertilizer can achieve high grain yield and low GWP. [ABSTRACT FROM AUTHOR]

Highlights: [•] Adjusting fertilization to the crop requirements reduces the N balance in a farmer's field. [•] N mineralized in spring is only utilized by the following summer-crop. [•] N application above crop requirements increases the amount of cycling N and apparent N loss. [Copyright &y& Elsevier]

Highlights: [•] Corn and pea ahead of wheat did not increase wheat WUE in the central Great Plains, USA. [•] Corn ahead of proso millet did not increase proso millet WUE. [•] Dryland wheat yield was not increased with corn included in a rotation. [•] Growing pea ahead of wheat decreased wheat yield. [•] Growing corn ahead of proso millet decreased millet yield. [ABSTRACT FROM AUTHOR]

Ear nitrogen (N) accumulation plays an imperative role in ear photosynthesis and the formation of grain yield and quality of maize and wheat. However, the mechanism governing ear N accumulation (NAe) especially under different N levels is not yet clear. For this purpose, this study endeavored to describe the N source-sink ratio of NAe by developing a model using ear critical N concentration (%Nc) dilution curves of maize and wheat. The data obtained include ear dry matter (DMe), NAe, ear N nutrition index (NNIe), ear N accumulation rate index (NARIe), post-anthesis N uptake (PANU), grain number (GN), and thousand-grain weight (TGW) were collected from 12 varied N rates (0–300 kg N ha−1) field experiments conducted using four wheat and three maize cultivars. Integrated models were developed to show the effect of N source and sink on NAe in maize and wheat. The ratio between PANU and NAe was used to represent the post-anthesis supply capacity of N source, while DMe was used as the storage capacity of N sink in these models. Robust relationships of NARIe with the ratio between PANU and NAe in maize and wheat indicated that NAe was controlled by N source from N-limiting to non-N-limiting levels. The relationship between the rate of ear dry matter accumulation (DMRe) and NNIe showed a linear plateau model across different N levels due to the similar DMe under non-N-limiting levels, indicating that ear N status was regulated by DMe (N sink) under N-limiting levels. Therefore, NAe under N-limiting levels was co-regulated by N source and sink. Besides, the temporal effect of plant N status before anthesis on NAe was also observed. The close relationship between DMe and plant N status at anthesis across different N levels in maize and wheat indicated that the potential ear N sink was controlled by the pre-anthesis supply capacity of plant N source. Consequently, pre-anthesis plant N status was imperative for quantifying potential ear N sink. This was the first-ever attempt to investigate the N source-sink ratio of NAe using ear %Nc curve and highlighted the effect of pre-anthesis plant N status on NAe. The findings will contribute towards a better understanding of the process of NAe under different N levels for developing a judicious N management strategy for improving the N use efficiency of wheat and maize. • Ear critical nitrogen (N) concentration dilution curve can be used to analyse the source-sink ratio of ear N accumulation. • Ear N accumulation is controlled by N source under non-N-limiting levels. • Ear N accumulation is co-limited by N source and N sink under N-limiting levels. • The N sink under N-limiting treatments has a close association with plant N status at anthesis. [ABSTRACT FROM AUTHOR]

Abstract: Zinc (Zn) is an essential mineral nutrient for plant and human growth, and dietary Zn deficiency is a worldwide nutritional problem. Using different Zn fertilizer application methods, this study determines the potential of increasing the Zn concentrations of maize and wheat grain to improve the nutritional status of local residents. Field trials were conducted in the Loess Plateau for two growing seasons to investigate the effects of different Zn fertilizer application methods on the grain Zn concentrations of maize and wheat as well as the grain Zn recovery, yield, and iron (Fe) status of grains under rain-fed conditions. Soil and foliar Zn application did not significantly affect the biomass and grain yield of maize and wheat, suggesting that local soils are not Zn deficient. However, foliar Zn application significantly improved the grain Zn concentration of maize by 27% and 37% and of wheat by 28% and 89% during the first and second growing seasons, respectively. The maize grain Fe concentrations during both growing seasons were also enhanced by foliar Zn application. The foliar application of Zn realized higher grain Zn recoveries of 35.2‰ and 42.9‰ in maize as well as 26.4‰ and 32.3‰ in wheat during the first and second growing seasons, respectively, compared with the soil Zn application with a maximum grain Zn recovery of 1.7‰. Hence, in the Loess Plateau in China, foliar Zn application is an economical method of improving the grain Zn concentration in maize and wheat and increasing grain Fe concentration in maize. [Copyright &y& Elsevier]

Abstract: Wheat–maize double cropping is the most important cropping system on the Hebei Plain and is one of the most important cropping systems in China. In a scenario of greater food demand, and increasing water and rural labour scarcity, it is critical that the annual productivity of the system is improved in water-energy-cost efficient and low carbon ways. Based on farm surveys, this paper benchmarked the performance of wheat–maize double crops on the Hebei Plain during the 2004–2005 season. These farm yields were assessed both against experimental yields collected from on-farm maximum yield trials conducted during the same 2004–2005 season and relative to simulated estimates of the climate-driven potential productivity of the region. The survey of 362 farms in six counties of the Hebei Plain during the 2004–2005 season found wheat yields ranging from 3375kgha−1 to 9000kgha−1 with an overall average yield of 6556kgha−1. Maize yields averaged 7549kgha−1 and ranged from 3375kgha−1 to 11,250kgha−1. The aggregate production for the wheat–maize double crops grown in the 2004–2005 season averaged 14,105kgha−1 across the six counties. This was 72% of the average production (19,586kgha−1) recorded from on-farm trials conducted in each of the six counties and 60% of the simulated average production potential (24,147kgha−1) for the Hebei Plain in the 2004–2005 season. Thus, the annual productivity of the current cropping system could be increased with currently available technologies by 28%, while a yield increase of 42% is possible if farm yields approach the simulated yield potential. Based on farmer interviews and field observations, a number of real and perceived reasons for the current yield gaps in farmers’ fields were recognised. For instance, irrigation at stem-elongation of wheat is a current recommendation, yet only a proportion of the surveyed farmers were able to follow this strategy due to lack of access to shared irrigation facilities. Improving the region''s infrastructure to enable more timely irrigation of crops will be a necessary prerequisite to improved productivity. The results from the farm surveys and on-farm trials indicate that, with current recommended practices, farmers can improve their annual farm productivity and close the current yield gaps. However, the survey identified that increasing system performance and efficiency will require a focus on both agronomic and socio-economic issues. [Copyright &y& Elsevier]

Abstract: Simple plant-based diagnostic tools can be used to determine crop P status. Our objectives were to establish the relationships between P and N concentrations of the uppermost collared leaf (PL and NL) of spring wheat (Triticum aestivum L.) and maize (Zea mays L.) during the growing season and, in particular, to determine the critical leaf P concentrations required to diagnose P deficiencies. Various N applications were evaluated over six site-years for wheat and eight site-years for maize (2004–2006) with adequate soil P for growth. Phosphorus and N concentrations of the uppermost collared leaf were determined weekly and the relationships between leaf N and P concentrations were established using only the sampling dates from the stem elongation stage for wheat and from the V8 stage of development for maize. Leaf P concentration generally decreased with decreasing N fertilization. Relationships between PL and NL concentrations (mgg−1 DM) using all site-years and sampling dates were described by significant linear–plateau functions in both maize (PL =0.82+0.089NL if NL ≤32.1 and PL =3.7 if NL >32.1; R 2 =0.41; P <0.001) and wheat (PL =0.02+0.106NL if NL ≤33.2 and PL =3.5 if NL >33.2; R 2 =0.42; P <0.001). Variation among sampling dates in the relationships were noted. By restricting the sampling dates [413–496 growing degree days (5°C basis) in wheat (i.e., stem elongation) and 1494–1579 crop heat units in maize (i.e., silking), relationships for wheat (PL =0.29+0.073NL, R 2 =0.66; P <0.001) and maize (PL =1.04+0.084NL, R 2 =0.66; P <0.001) were improved. In maize, expressing P and N concentrations on a leaf area basis (PLA and NLA) at silking further improved the relationship (PLA =0.002+0.101NLA, R 2 =0.80; P <0.001). Predictive models of critical P concentration as a function of N concentration in the uppermost collared leaf of wheat and maize were established which could be used for diagnostic purposes. [Copyright &y& Elsevier]

Abstract: Achieving high productivity using organic manure as a source of N offers new soil management possibilities in intensive agriculture. Our objective was to study the growth response of winter wheat (Triticum aestivum) to different fertilization regimes in long-term experiments in Japan. Semi-dwarf wheat varieties were grown in crop rotation with maize (Zea mays) with a high rate of organic manure (OM; 80tha−1 yr−1 for >10years, estimated N application rate is 739kgNha−1 yr−1), and standard (SF; 204–252kgNha−1 yr−1) or low (LF; 102–126kgNha−1 yr−1) rates of inorganic fertilizer for 3 years. We observed greater biomass production in OM than in SF or LF, which was attributable to a higher leaf area index, leaf N status, and stomatal conductance in OM. Grain yield in OM (6.6–8.9tha−1) was significantly higher than that in LF (3.5–6.6tha−1) for both cultivars, and comparable to that in SF (6.6–8.5tha−1). However, the dry matter partitioning during the grain-filling period suggested an imbalance in the sink–source relationship in OM: the number of grains was too large for the assimilation rate. Varietal differences in grain weight in OM resulted from differences in dry matter production during grain filling and, to a lesser extent, differences in grain density. The growth pattern of wheat under intensive manure application should be modified to favor biomass production during the post-anthesis stages. Based on our results, we discuss possible strategies for wheat improvement under high soil fertility in Japan. [ABSTRACT FROM AUTHOR]

Abstract: Crop growth and development as well as yield are the result of the efficiency of the chosen agricultural management system within the boundaries of the agro-ecological environment. End-of-season yield results do not permit the evaluation of within-season management interactions with the production environment and do not allow for full understanding of the management practice applied. Crop growth and development were measured during the 2004, 2006 and 2008 crop cycles with an optical handheld NDVI sensor for all plots of the different management treatments of a long-term (since 1991) sustainability trial in the highlands of Mexico. Cropping systems varying in (1) tillage (conventional vs. zero tillage); (2) residue management (retention vs. removal); (3) rotation (monocropping vs. a maize [Zea mays L.]/wheat [Triticum aestivum L.] rotation) were compared. The NDVI-handheld sensor was evaluated as a tool to monitor crop growth and development and was found to be an excellent tool for this purpose. There was a strong relation between NDVI and biomass accumulation of maize and wheat. The measurement with the handheld sensor was non-destructive and fast so that a representative plot area could be measured easily and time-efficiently. Zero tillage induced different crop growth dynamics over time compared to conventional tillage. Zero tillage with residue retention is characterized by a slower initial crop growth, compensated for by an increased growth in the later stages, positively influencing final grain yield. Also crop rotation influenced early crop growth, with lower NDVI values for crops sown after wheat than crops after maize. Zero tillage with residue removal had low NDVI values throughout the growing season. Zero tillage with retention of crop residues results in time efficient use of resources, as opposed to conventional tillage, regardless of residue management, and zero tillage with residue removal. The results indicated that different tillage, rotation and residue management practices influence crop growth and development. It is important to monitor and understand crop growth under different management systems to select the right varieties and adjust timing and practice of input supply (fertilizer, irrigation etc.) in a holistic way in each cropping system. [Copyright &y& Elsevier]

Abstract: Efficiency of fertilizer N is becoming increasingly important in modern agricultural production owing to increasing food requirement and growing concern about environments. However, there is almost no study regarding its long-term efficiency in wheat and maize cropping systems. Long-term (15 years) experiments involving wheat (Triticum aestivum L.) and maize (Zea mays L.) rotations at five field sites with various soil and climate characteristics in China were used to determine the nitrogen (N) efficiency, including the physiological efficiency, recovery efficiency and N mass balance of soil–plant systems in response to different fertilization treatments. The present study consisted of nine treatments: unfertilized, N, phosphorus, potassium, straw and manure or their combinations. The contribution of N fertilizers to wheat yield was higher than to maize and suggested that wheat could be given priority over maize when determining N application rates. Uptake of 1kg N produced 35.6kg of wheat grain and 39.5kg of maize grain. The deficit of N in soils without applied N ranged from 40 to 103kgNha−1 year−1, while N surpluses in soils with applied N fertilizers ranged from 35 to 350kgNha−1 year−1. The apparent accumulated N recovery efficiency (NREac) varied widely from 4% to 90%: unbalanced fertilization and other soil limiting factors (such as aluminium toxicity) were associated with low NREac. In the treatments of combination of N, phosphorus and potassium with normal application rates, the average of NREac in four out of five sites reached 80%, which suggested that best management of N fertilizers could recover most of N fertilizers applied to soils. The results will be helpful to understand the long-term fate of N fertilizers and to optimize the N fertilization for agricultural practices and environment protection. [Copyright &y& Elsevier]

• Rainfed wheat/maize intercropping provided land equivalent ratios above 1. • Wheat in first border rows and second border rows showed major yield increase. • The yield components resulted in intercropped wheat yield increase were different. • The SPAD and Pn in border rows of intercropped wheat were significantly improved. • The SPAD and Pn of intercropped maize showed growth recovery after wheat harvest. Intercropping has been widely adopted by farmers for higher yield compared to monoculture, and the border effect was responsible for the yield advantage in irrigated areas. However, few studies have investigated the border effect based on photosynthesis, especially under rainfed conditions. Here, we evaluated the yield in rainfed wheat/maize strip relay intercropping, and explored the associated differences in yield components and physiological process compared to sole crops. A two-year field experiments was conducted including three treatments (sole wheat, sole maize and wheat/maize intercropping) in Yangling, located in the semi-humid region of northwest China. Grain yield, yield components, chlorophyll relative content (SPAD) and photosynthetic parameters in different rows were measured for wheat and maize. Results showed that wheat/maize intercropping increased the land use efficiency and total yield of wheat and maize under rainfed conditions. The yield of intercropped wheat was significantly (p < 0.05) increased by 35% on average over two years, resulting not only from the first border rows but also from the second border rows. The yield improvement in the first border rows relative to sole wheat was attributed to the increase of ear number (56%, p < 0.05), kernel number per ear (14%, p < 0.05) and thousand kernel weight (12%, p < 0.05), but the yield improvement in the second border rows was only attributed to the ear number (22%, p < 0.05). The yield of intercropped maize was not significantly (p > 0.05) decreased (6%), mainly attributed to the border rows (19% lower than in sole maize), in which the kernel number per cob and thousand kernel weight were 14% and 8% (p < 0.05) lower than that in sole maize. This was because that the SPAD and photosynthetic rate of maize in intercropping was suppressed during the co-growth period (about 62 days). Although the two had a partly growth recovery after wheat harvest, the growth recovery was not complete, and this was responsible for the reduction of maize yield in intercropping. This study demonstrates that the importance of yield components and the photosynthesis basis for yield advantage in intercropping systems, and reducing the adverse effect of dominate crop on subordinate crops could better exert the advantages of intercropping. [ABSTRACT FROM AUTHOR]