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Despite conservation agriculture (CA) is being promoted as a climate resilient technology, limited information is available on its impacts on N storage within soil aggregates vis a vis global warming potential (GWP) under tropical agro-ecosystems. Hence, this study assessed the effects of a medium-term (5-years) CA on total soil N (TSN) changes in bulk soils and aggregates, N 2 O and CO 2 emission, GWP and total C fixed in soils under maize ( Zea mays L.)- wheat ( Triticum aestivum L.) system on the Indo-Gangetic Plains (IGP). The treatments were: conventional tillage (CT), zero tillage (ZT) with planting on permanent narrow beds (PNB), PNB with residue (PNB + R), ZT with planting on permanent broad beds (PBB), PBB with residue (PBB + R), ZT on flat land/plains without crop residue (ZT) and with crop residue retention (ZR + R). Soil samples were collected after five years of a maize–wheat system and TSN in bulk soils and their aggregates of the 0–5 and 5–15 cm soil layers were measured along with N 2 O and CO 2 emissions during the fifth year (2014–15).The soils under PBB + Rhad 37 and 9% more macro-aggregate-and micro-aggregate-associated N concentrations in topsoil (0–5 cm layer) than CT (248 and 299 kg N ha −1 ). However, topsoil soil aggregation and aggregate-associated N contents of PNB + R and ZT + R were similar to CT plots. The dehydrogenase and fluorescein diacetate activities and TSN, microbial biomass N, NO 3 -N and NH 4 -N concentrations were also highest in PBB + R plots in topsoil. The topsoil dehydrogenase activity was significantly correlated (r = 0.426, n = 21, p < 0.05) with CO 2 emission and with N 2 O emission (r = 0.770, n = 21, P < 0.01) during wheat (2014–15). However, topsoil FDA activities and MBN concentrations were only significantly correlated with N 2 O emission in wheat. In the maize–wheat system, highest N 2 O emission was observed in PNB + R plots and least in CT plots. But, PBB + R and PNB + R plots had similar CO 2 emissions to CT plots in both crops. Despite GWP of ZT + R and PBB + R plots in the maize-wheat system were ∼5% higher than CT, greenhouse gas (GHG) intensities in the CT, PBB + R and ZT + R plots were similar. Thus, PBB + R practice is a better management alternative for soil N improvement (and a reduced fertilizer N dose could be adopted in future) than CT since this practice also had 36% and 8.2% higher biomass productivities of maize and wheat, respectively in the maize-wheat cropping system and similar GHG intensity to CT plots. [ABSTRACT FROM AUTHOR]

No-tillage of summer maize after the harvest of winter wheat is the main agricultural practice on the Huang-Huai-Hai (HHH) Plain of China. However, long-term no-tillage in the absence of deep tillage practices affects soil properties, and this effect is not beneficial for the growth and yield production of summer maize. Field experiments were conducted in 2016 in two agricultural sub-zones (Luancheng and Guoyang) in the HHH Plain. The main objective of this study was to evaluate the effect of deep vertical rotary tillage (DVRT), compared to no-tillage with strip subsoiling (NTSS), on dry matter accumulation (DMA) and yield formation. DVRT significantly reduced the soil bulk density of the top soil layer (0–40 cm), especially for the lime concretion black soil in the Guoyang experimental site. Compared with NTSS, the soil water content in the 20–60 cm soil layer was increased under the condition of DVRT. DVRT also significantly increased root DMA in the 0–30 cm soil layer in Luancheng and in the 0–40 cm soil layer in Guoyang. The total shoot DMA, seed DMA, and harvest index of DVRT were significantly higher than those of NTSS, primarily due to a significant increase in post-anthesis DMA. In addition, DVRT increased the maximum and mean grain filling rate and thus significantly increased the maximum grain weight at harvest. Compared with NTSS, DVRT significantly increased grain yield by 21.3% and 27.8% under the plant density of 6.75 pl m −2 and 9 pl m −2 , respectively, in Luancheng and it increased by 12.3% in Guoyang. The present results indicate that DVRT can be used as a deep tillage practice to improve soil properties and grain yield of summer maize, and this may provide guidance regarding the requirements to cope with a diversity of deep tillage machines and develop sustainable agriculture in the HHH Plain of China. [ABSTRACT FROM AUTHOR]

As phosphorus (P) is a finite, non-renewable resource, it should be used as efficiently as possible. Different placement methods (broadcast, band, deep band, and others) can optimize the P supply for plants. Therefore, this meta-analysis evaluated 39 studies involving four major crops wheat (Triticum aestivum L.), maize (Zea mays L.), soybean (Glycine max L.), and oilseed rape (Brassica napus L.) concerning the effectiveness of different P placement methods on yield, yield parameters, and P uptake. Most authors indicated yield advantages in wheat and maize when P fertilization was applied in bands. This was confirmed by the meta-analysis indicating that especially P application in the deep band leads to yield advantages in wheat and maize. Phosphorus placement's influence on yield, yield components, and P uptake was affected by external factors, such as the site, the year of cultivation, and the crop variety. In the case of oilseed rape (Brassica napus L.), band application advantages were also demonstrated. Broadcast P was the best overall application for soybean. Further research is needed to better understand the interactions between pH, soil P content, P placement, and yield effects. • Efficiency of different P placement methods. • Interactions of soil test P, pH, soil moisture, and phosphorus pool with P placement. • Influence of P placement on yield and P uptake of different crops. • Band application of P recommended for wheat, maize, and oilseed rape. • Broadcast application of P recommended for soybeans. [ABSTRACT FROM AUTHOR]

Abstract: Seed placement and failure to establish a uniform plant stand are critical problems associated with conservation tillage production of corn (Zea mays) following wheat (Triticum aestivum) in Iran. Our objectives were to evaluate the performance of a conventional corn planter (with runner type openers) equipped with row cleaners and to demonstrate for local farmers an affordable method for reduced tillage corn production. The reduced tillage system studied consisted of disking followed by chisel plowing and another disking ahead of planting. A ground-driven row cleaner was fabricated and mounted to each unit of a common pneumatic single seed planter and used to plant at three forward speeds (4, 7, and 10kmh−1) into no- (NR), half- (HR), and whole- (WR) residue plots. This compares to a typical system of complete removal or burning the previous wheat residue in the region. The amount of residue retained in the row, depth of seed placement, emergence rate and three indices of uniformity in seed spacing were determined. Row cleaners performed best at the highest forward speed, retaining an average residue cover of 920kgha−1 compared to 1350kgha−1 for plots planted without using row cleaners. This 430kgha−1 more residue removal was a significant improvement with regard to soil–seed contact. For the HR and WR plots, residue removal averaged 45% and 70% of that present before planting, suggesting that the row cleaners will work more effectively at high residue conditions. Without row cleaners, initial residue levels resulted in a shallow planting depth, but when row cleaners were used, planting depth was maintained near the target depth (5cm). The desired planting depth was also obtained at 7kmh−1 in the HR plots. Row cleaners significantly increased plant emergence rate with the maximum (3.5plantsd−1 m−1) being observed for seeds planted at 4kmh−1 in the HR plots. This agrees with others who showed high residue reduces plant emergence and grain yield. Planting with row cleaners into HR plots at 7kmh−1 resulted in the lowest miss and precision indices comparable to those of a no-residue plot (16.5% and 17.5%, respectively), and a quality of feed index as high as 69% was obtained at similar conditions. Our results indicate that equipping available planters with row cleaners can result in a successful reduced tillage corn production system and thus satisfy both farmers and authorities promoting conservation tillage. In addition to the environmental benefits of the proposed system, it is expected that the savings in time, fuel and labor would offset the cost of row cleaners. [Copyright &y& Elsevier]

Abstract: No-tillage is an increasing way of management for agricultural soils. The objective of this study was to identify in which extent the chemical properties of a loamy soil could be affected by no-tillage under temperate conditions. Soil chemical properties were investigated on a field subjected to either conventional or no-tillage management of maize (Zea mays L.) and wheat (Triticum aestivum L.) with identical fertilization practices and no lime supply since 1970. On no-tilled soil, maize was cropped exactly on the same line every other year, which enabled soil sampling under the row and under the interrow. Tilled soil had an homogeneous ploughed horizon, whereas soil under no-tillage exhibited strong vertical gradients of pH, exchangeable cations and organic C. No-tilled soil had 11.4% greater organic C than tilled soil, and the difference was concentrated in the upper 5cm. The proportion of exchangeable cations was highest in the interrow of no-tilled soil and lowest in tilled soil. Tilled soil contained much lower exchangeable K than no-tilled soil, indicating a difference in retention capacity of this cation. The pH of the upper 5cm of no-tilled soil was low, probably because of surface accumulation of organic residues. Whatever the tillage system, exchangeable Al was significantly related to pH according to the relation: Alex =76441×10−0.99pH (r 2 =0.96; p <0.001). An expected complexing effect of organic matter on Al was not observed, probably hidden by the influence of pH. Since yields were not negatively affected by long-term no-tillage and organic C content was higher, no-tillage appears to be a cost-saving choice for maize and wheat production under these temperate environmental conditions, as well as a way for C sequestration. [Copyright &y& Elsevier]

The objective of this study was to determine in a long-term experiment (13 years) the effect of three different crop rotations (R1: wheat (Triticum aestivum)–soybean (Glycine max), R2: wheat–soybean–vetch (Vicia villosa)–maize (Zea mays), and R3: wheat–soybean–oat (Avena sativa)–soybean–vetch–maize) under zero tillage (ZT) and conventional tillage (CT) on the stocks of soil organic matter (SOM) in a clayey Oxisol soil of Passo Fundo, Rio Grande do Sul. At the end of 13 years, soil samples were taken to a depth of 100 cm, and analysed for bulk density, chemical composition and 13C natural abundance. Under a continuous sequence of wheat (winter) and soybean (summer) the stock of soil organic C to 100 cm depth under ZT (168 Mg ha−1) was not significantly different (LSD at P=0.05 of 11 Mg ha−1) to that under CT (168 Mg ha−1). However, in the rotations with vetch planted as a winter green-manure crop (R2 and R3), soil C stocks were approximately 17 Mg ha−1 higher under ZT than under CT. Between 46 and 68% of this difference occurred at 30–85 cm depth. The 13C abundance data indicated that under ZT the decomposition of the original native SOM was not affected by the different composition of crops in the different rotations, but under CT the rotations R2 and R3, which included vetch and maize, stimulated the decay of the original native SOM compared to the continuous wheat/soybean sequence (R1). It appears that the contribution of N2 fixation by the leguminous green manure (vetch) in the cropping system was the principal factor responsible for the observed C accumulation in the soil under ZT, and that most accumulated C was derived from crop roots. [Copyright &y& Elsevier]

Inverse linear relationships between soil strength and yield in Coastal Plain soils that have subsurface genetic hard layers have previously been developed for corn (Zea mays L.), soybean (Glycine max L. Merr.), and wheat (Triticum aestivum L.) grown under management systems that include annual or biannual non-inversion deep tillage. In a field study in the southeastern Coastal Plains of the USA, we tested this relationship for cotton (Gossypium hirsutum L.) grown in wide (0.96 m) rows, hypothesizing that root growth and lint yield of cotton would increase with a decrease in soil strength associated with annual deep tillage or cover crop. Root growth and yield were evaluated for treatment combinations of surface tillage or none, deep tillage or none, and rye (Secale cereale L.) cover crop or none. Root growth increased (r2=0.66–0.68) as mean or maximum soil strength decreased. Cotton lint yield was not significantly affected by the treatments. Lack of yield response to tillage treatment may have been the result of management practices that employed a small (3 m wide) disk in surface-tilled plots and maintained traffic lanes, both of which help prevent re-compaction. These results indicate that less than annual frequency of subsoiling might be a viable production practice for cotton grown in traditionally wide (0.96 m) rows on a Coastal Plain soil (fine loamy Acrisol–Typic Kandiudult). Thus, annual subsoiling, a practice commonly recommended and used, need not be a blanket recommendation for cotton grown on Coastal Plain soils. [Copyright &y& Elsevier]

Recent research has indicated that conservation systems with narrow-rows have potential for higher crop productivity on southeastern USA Coastal Plains Soil. The objective of this study was to determine how surface tillage and subsoiling affect nutrient distribution in the soil profile in narrow- and wide-row systems. A secondary objective was to determine the effect of row position on soil pH and nutrient concentrations in the wide-row system. Soil samples were collected in 1996 from plots that had been growing soybean (Glycine max (L.) Merr.) double cropped with wheat (Tritiucum aestivum L.) for 3 years and then again in 1999 after 3 years of continuous corn (Zea mays L.). Narrow-row spacing was 19 cm for soybean and 38 cm for corn. Wide-row spacing was 76 cm for both soybean and corn. Wheat was grown in 19 cm wide-rows. Soil samples were randomly collected from throughout the plots in the narrow-row culture. In the wide-row culture, separate samples were collected from the row and from between rows. Treatments were surface tillage (disc tillage (DT) and no surface tillage (NT)), with different frequencies of subsoiling. The soil type was Goldsboro loamy sand (fine-loamy, siliceous, thermic, Aquic Kandiudult). Soil samples from four depths (the surface 5 cm of the A horizon, the remainder of the A horizon, the E horizon, and the top 7.5 cm of the B horizon) were analyzed for pH, P, K, Ca, and Mg. Nutrient concentrations and pH differed little between row spacings at any depth after either 3 or 6 years. Differences due to subsoiling appeared mainly due to nutrient removal as the treatments with more intense subsoiling had higher yield and lower concentrations of nutrients (except K). Concentrations of P, Mg, and Ca at the soil surface tended to be higher in NT than in DT, especially in the mid-rows of the 76 cm wide-row systems. The data suggest only small differences in soil nutrient stratification can be expected as growers adopt narrow-row crop production systems with intensive subsoiling. [Copyright &y& Elsevier]

• Soil moisture has the potential to be used as a measurement of the resiliency. • We examined the applicability of four soil moisture metrics to measure resiliency. • These metrics helped with identifying promising treatments to address resiliency. • No-till and reduced input treatments were the most and least promising. Measuring and improving resiliency is the key goal of climate risk management in rainfed agriculture. Currently, available metrics are generally used to qualitatively measure the resilience of agricultural systems at broader scales. Moreover, these metrics showed non-linear responses to climate variability, thus often fail to capture the temporal dynamics of resilience at field scales. Our objective for this study is to combine a few soil moisture-based metrics to gauge the resiliency of three promising rainfed agricultural treatments, namely the no-till, organic, and reduced input treatments against the conventional treatment. These treatments have been established at the Kellogg Biological Station Long-Term Ecological Research (KBS-LTER) experiment in a randomized complete block design with six blocks per treatment. All four of these treatments consisted of maize (Zea mays)-soybean (Glycine max)-winter wheat (Triticum aestivum) in rotation. Long-term (1993–2018) soil moisture data from this experiment was collected to compute the soil moisture metrics while the total crop biomass, crop yield, and soil organic carbon data were statistically analyzed to evaluate the robustness of the metrics to gauge the resiliency of these systems. Results have shown that, among the soil moisture metrics, the mean relative difference, the Spearman's rank correlation coefficient, and soil water deficit index were suitable, while the index of temporal stability was not suitable to gauge the resiliency of different rainfed agricultural systems. The no-till treatment was identified as the most resilient treatment in terms of soil moisture retention, effectiveness for drought mitigation, and crop yields. Meanwhile, the reduced input treatment was the least resilient in terms of soil water conservation and drought recovery. The results of this study can be extended to other Midwest regions of the United States and similar climatological areas around the world. [ABSTRACT FROM AUTHOR]

• 75% N in NT and CT increased SOC and STN compared to 100% N. • Soil quality, wheat and maize yields can be maintained by 75% N fertilizer. • The yield stability of the maize is greater than that of wheat. • CT increased yield stability and SOCS in 0–40 cm compared to NT. • NT increased STN concentration, STNS and NSR in 0–20 cm compared to CT. Excessive nitrogen (N) fertilizer application can cause resource waste and environmental pollution. Thus, whether the rate of N applied can be decreased under no-tillage, which usually increases soil carbon (C) and N stocks, has become an important topic. We hypothesized that a certain extent of N fertilizer application decrease under no-tillage can still maintain higher soil C and N stocks and yields of wheat and maize, however, the effects under different tillage systems may be different. To find the appropriate N fertilizer applications and tillage methods to keep higher soil C and N and crops yields, 10 treatments, including 2 tillage patterns (conventional tillage: CT and no-tillage: NT) and 5 fertilization rates (100%, 75%, 50%, 25% and 0 N of the common N fertilizer application), were tested in triplicate via a randomized block design on a Hapli-Udic Argosol during 2006–2016. The annual wheat and maize yields of 100% N, 75% N and 50% N under CT and NT treatments were significantly higher than those of 25% and 0 N on the studied period (P < 0.05). Higher yield stability of the wheat and maize were found under 75% and 50% N application compared to other N rates. However, the yield stability of wheat was lower than that of maize. The SOC concentration, SOCS and CSR of 75% N application were increased by 1.5, 2.2 and 20.6% than those of 100% N application respectively, in the 0–40 cm soil depth. The STN concentrations of NT-100 and NT-75 were significantly higher than those of other treatments (P < 0.05). The STNS and NSR in the NT-100 treatment were significantly higher than those of other treatments (P < 0.05). NT could lead to more accumulation of SOC and STN in the surface soil depth (0–20 cm) during 2007–2016. In conclusion, 75% of the common N application rate under NT and CT were better choices for sustainable agricultural development. [ABSTRACT FROM AUTHOR]