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The editorial discusses the importance of cover crops and green manures in providing essential ecosystem services to agroecosystems. It highlights the impact of agriculturization on soil health and the benefits of sustainable management practices, such as integrating cover crops into crop rotations. The research topic compiled studies that focused on nutrient cycling, soil fertility, plant nutrition, and environmental benefits of cover crops and green manures. The findings emphasize the multifaceted role of these crops in enhancing agroecosystem services and the need for a holistic approach to evaluate their contributions effectively. [Extracted from the article]

Cover crop (CC) inclusion in cropping sequences could ameliorate negative effects of continuous agriculture on soil properties. The use of CC as a sustainable management tool can reverse the soil degradation process and improve soil health in the short term. The present study evaluated soil properties following short-term cover cropping in on-farm conditions. Three strip-trial experiments were conducted. Treatments were: i) oat (Avena sativa), ii) vetch (Vicia villosa), and iii) control (without CC). Prior to CC chemical termination, shoot and root dry matter (DM) and DM nitrogen accumulation in CC shoot (Nac) were determined. After CC termination, we determined: soil bulk density (BD), penetration resistance (PR), infiltration (INF), aggregate stability, total and particulate organic carbon (POC), organic nitrogen, nitrogen mineralized in anaerobic incubation (Nan) and soil glomalin. On average across sites, grater shoot, and root DM were determined in oat than vetch, while Nac was greater in vetch. The POC and Nan increased by CC inclusion mainly in 0–5 cm soil depth. Improvements of over 50% in INF (0–20 cm) and 8% in BD (0–5 cm) were determined in CC treatments compared to control. The effects of CC on some soil parameters depended on the previous management practices (i.e. tillage system, crop sequences). In the short-term, CC inclusion improves some soil properties, depending on their sensibility to management practices. [ABSTRACT FROM AUTHOR]

Nitrogen (N) deficiency could have a negative effect on sunflower (Helianthus annuus L.) yield and grain quality. Therefore, it is necessary to adjust the optimum rate, timing, and frequency of N fertilization to improve sunflower crop nutrition. Our objective was to evaluate the effect of N fertilization rate, timing, and splitting on grain yield, and grain and oil quality. Twelve field experiments were carried out between 2016 and 2020. Treatments consisted of at least three N rates ranging from 0 to 200 kg N ha−1 applied at V2. Moreover, the 80 kg N ha−1 rate was applied at V14 (80NV14) or split between V2 and V14 (80Nsplit). Treatments were evaluated in two sunflower genotypes, high oleic (HO) and conventional (CONV). A significant grain yield response to N fertilization was observed in six out of twelve experiments, generally at rates greater than 80 kg ha−1. The mean response to fertilization was 369 kg ha−1. Fertilization increased grain protein concentration (PG) (+1.5%) at experiments E1–E3 and E9–E12 and decreased oil concentration (OG) (−2%) at experiments E1, E4, E9, E11, and E12. The maximum N rate, increased oleic and stearic acid concentration (+3%–4%), depending on the genotype (AO and CONV). Neither fertilizer timing nor splitting affected grain yield or OG. Late N fertilization (V14) increased oleic acid (+2.4%), whereas it decreased linoleic acid (+2.2%). Based on our results, N fertilization can increase yield without negatively affecting commercial grain quality (OG and fatty acids concentration), regardless of fertilization timing and frequency. Core Ideas: Nitrogen fertilization at a rate >80 kg N ha−1 maximizes sunflower yield.Increases in N rate enhance oleic and stearic concentration.N fertilization at V14 increases protein concentration.Nitrogen timing and splitting do not affect yield nor grain quality. [ABSTRACT FROM AUTHOR]

The objectives were to i) assess the effect of enhanced-efficiency nitrogen (N) fertilizers (EENF) [maleic itaconic acid copolymer (NSN) or 3,4-dimethylpyrazole phosphate (DMPP)] and urea on potato (Solanum tuberosum L.) tuber yield, N agronomic efficiency (NAE), N recovery efficiency in tuber (NREtuber) and plant (NREplant), N physiological efficiency, residual inorganic N in soil at harvest (Nresidual) and N losses (Nlosses) and ii) determine the impact of the amount of drainage water on NAE and Nlosses. On-farm experiments were conducted in seven sites with two fertilizers (EENF and urea) and two N rates (0 and 100 kg N ha−1). A N mass balance was used to calculate Nlosses. At two sites (one with NSN and one with DMPP), tuber yield response to N was greater with EENF than urea (avg. 5.0 Mg ha−1). NAE, NREtuber and NREplant were 17%, 31% and 25% higher with EENF than urea, respectively. These efficiencies decreased as drainage water increased. The estimated Nlosses were 12% lower with EENF, being the reduction particularly relevant with increasing drainage water. Therefore, using EENF in combination with irrigation management that ensures low drainage water amounts is essential for maximizing the fertilizer use efficiency and minimizing Nlosses in potato production systems. [ABSTRACT FROM AUTHOR]

The malt industry has specific requirements for malting barley (Hordeum vulgare L.) grain protein concentration (from 9.5 to 13%) and size (>85%), which could be affected by nitrogen (N) fertilization. We aimed to (a) define and explain the economic optimum nitrogen rate (EONR) for grain yield in feed (EONRf) and malting barley (EONRm), and (b) analyze if grain quality requirements are reached at the EONRm. We evaluated six N rates (0, 40, 80, 120, 160, and 200 kg N ha−1) in field experiments (14 site‐years). At each site‐year, the EONR was calculated using two fertilizer cost to grain price ratios, 6:1 for feed and 4:1 for malting barley. On average, maximum yield and protein response to N were 1,681 kg ha−1 and 2%, respectively. There was no consistent effect of N fertilization on grain size. The EONRf was explained by N availability and maximum yield response to N (y = 130 – 0.37N availability + 0.03N response, r2 =.89), and EONRm was explained solely by N availability (y = 320 – 0.93N availability, r2 =.75). The overall EONRm was 134 kg N ha−1. At sites with low soil N availability and high yield response to N, an average N rate of 69 kg ha−1 greater than the EONRm was necessary to reach 9.5% protein. Otherwise, the EONRf could be used (106 kg N ha−1) and grains be sold as feed barley. These results are useful to adjust N fertilizer recommendations to satisfy the malting industry demand while reducing the economic and environmental impacts of fertilization. Core Ideas: The mean economic optimum N rate (EONR) for feed barley was 106 ± 48 kg N ha−1.The mean EONR for malting barley was 134 ± 55 kg N ha−1.N availability and maximum N response explained the differences in EONR.Sites with low N availability and high grain yield response to N did not reach 9.5% protein at the EONR.Grain size was within malting industry requirements, even at high N rates. [ABSTRACT FROM AUTHOR]

Monitoring the availability of phosphorus (P) in soil under continuous cropping facilitates finding deficiency in crops and contributes to improving crop growth and nutrient management models. Soil P availability for crops is usually estimated by soil test P (STP), such as Bray‐1. This is widely used in the Americas. The relationship between the decrease of STP Bray‐1 and cumulative removal of P was evaluated in non‐P‐fertilized areas in long‐term studies. This removal was the sum of annual P removal over the study period as P exported in grains/crop outside the soil. The objectives were to: (a) quantify changes in STP as a function of cumulative P removal, (b) assess the relationship between relative decrease rate of STP and soil variables as well as annual removal of P by crops, and (c) develop a model to predict decrease of STP Bray‐1. Exponential decay functions were used to describe annual cumulative removal of P and STP from soil over time for 12 long‐term studies where no addition of P fertilizer was carried out. Changes in the relative rate of decrease of STP, relative to the initial STP Bray‐1 value at the onset of the experiment, were predicted by the ratio of soil organic matter to clay and silt and the average annual P removal by exponential decay (R2adj = 0.64; RMSE = 3.2 mg kg−1). We propose this predictive model as suitable to provide estimates of the relative decrease rate of STP by Bray‐1 and thereby improve management of P for optimizing crop yield. Highlights: STP Bray‐1 decrease and cumulative P removal were related by exponential decay functions.Relative decrease rate of STP Bray‐1 was related to SOM/(clay+silt) ratio and annual P removal.A predictive model of the relative decrease rate of STP Bray‐1 was fitted and validate.Our model is a useful tool to help predict soil P availability and nutrient management. [ABSTRACT FROM AUTHOR]

Soybean [Glycine max (L.) Merr.] seeding rate research across North America is typically conducted in small geo‐political regions where environmental effects on the seeding rate × yield relationship are minimized. Data from 211 individual field studies (∼21,000 data points, 2007–2017) were combined from across North America ranging in yield from 1,000– 7,500 kg ha−1. Cluster analysis was used to stratify each individual field study into similar environmental (soil × climate) clusters and into high (HYL), medium (MYL), and low (LYL) yield levels. Agronomically optimal seeding rates (AOSR) were calculated and Monte Carlo risk analysis was implemented. Within the two northern most clusters the AOSR was higher in the LYL followed by the MYL and then HYL. Within the farthest south cluster, a relatively small (±15,000 seeds ha−1) change in seeding rate from the MYL was required to reach the AOSR of the LYL and HYL, respectively. The increase in seeding rate to reach the LYL AOSR was relatively greater (5x) than the decrease to reach the HYL AOSR within the northern most cluster. Regardless, seeding rates below the AOSR presented substantial risk and potential yield loss, while seeding rates above provided slight risk reduction and yield increases. Specific to LYLs and MYLs, establishing and maintaining an adequate plant stand until harvest maximized yield regardless of the seeding rate, while maximizing seed number was important with lower seeding rates. These findings will help growers manage their soybean seed investment by adjusting seeding rates based upon the productivity of the environment. [ABSTRACT FROM AUTHOR]

In the temperate-humid region of Argentina, nitrogen (N) fertilisers in maize (Zea mays L.) are mainly applied around sowing, whereas N-splitting is rare and occurs during early vegetative stages. Splitting and late N fertilisation, even up to silking (R 1), effects on yield have been recently studied. However, to the extent of our knowledge, these studies have mainly focused on the effect of these strategies on maize yield, but less on the crop N economy. The aims were to study the mechanisms explaining the effect of i) splitting N and ii) additional N application at R 1 on yield, post-flowering N uptake, kernel weight, N uptake efficiency, and the relationship of these variables with the N nutrition index (NNI). Seven experiments were carried out throughout the humid temperate region of Argentina, evaluating seven treatments: a control without N fertilisation, N rate entirely applied at sowing or split between sowing, eight leaf (V 8), and R 1 , an additional N rate at R 1 , and an N sufficiency treatment. The scenario with split N application had no adverse effect on either yield or N uptake at maturity (P > 0.05), with less pre-flowering N uptake compensated with more post-flowering N uptake in late N applications. In turn, increases in both yield and kernel weight were related to increases in post-flowering N uptake. Positive yield responses to N-splitting (plateauing at 450 kg ha-1) were obtained with yield responses to N greater than 3107 kg ha-1. Likewise, yield responses to additional N at R 1 (plateauing at 1107 kg ha-1) were evident with yield responses greater than 2943 kg ha-1. The NNI at R 1 accounted for variations in post-flowering N uptake and yield, as well as yield responses to additional N at R 1 and their impact on kernel weight. Results show that N-splitting and late N fertilisation are promising strategies that, combined with crop N status monitoring, could lead to improvements in both maize yield and N economy. • Split and late N fertilisations were evaluated for maize in the humid-temperate region of Argentina. • Grain yield (GY) responses to N-splitting and to additional N at R 1 were recorded. • GY responses to N-splitting and to additional N at R 1 were higher for the most responsive sites. • N-splitting did not reduce GY and increased N uptake efficiency. • GY response to additional N at R 1 was negatively associated with crop N status at R 1. [ABSTRACT FROM AUTHOR]

It is unclear if additional inoculation with Bradyrhizobia at varying soybean [Glycine max (L.) Merr.] growth stages can impact biological nitrogen fixation (BNF), increase yield and improve seed composition [protein, oil, and amino acid (AA) concentrations]. The objectives of this study were to evaluate the effect of different soybean inoculation strategies (seed coating and additional soil inoculation at V4 or R1) on: (i) seed yield, (ii) seed composition, and (iii) BNF traits [nodule number and relative abundance of ureides (RAU)]. Soybean field trials were conducted in 11 environments (four states of the US) to evaluate four treatments: (i) control without inoculation, (ii) seed inoculation, (iii) seed inoculation + soil inoculation at V4, and (iv) seed inoculation + soil inoculation at R1. Results demonstrated no effect of seed or additional soil inoculation at V4 or R1 on either soybean seed yield or composition. Also, inoculation strategies produced similar values to the non-inoculated control in terms of nodule number and RAU, a reflection of BNF. Therefore, we conclude that in soils with previous history of soybean and under non-severe stress conditions (e.g. high early-season temperature and/or saturated soils), there is no benefit to implementing additional inoculation on soybean yield and seed composition. [ABSTRACT FROM AUTHOR]

Core IdeasA simplified balance was used to calculate apparent S mineralization in wheat.Apparent S mineralization predicted relative wheat grain yield.Sulfate‐S before sowing combined with particulate organic C diagnosed S status.Sulfur mineralization in soil should be considered in diagnostic methods based on soil analysis. Consideration of S mineralization could aid the development of S diagnostic methods in wheat (Triticum aestivum L.) but this process has not been investigated under field conditions. The objectives of this study were to evaluate: (i) the use of a simplified S balance to quantify apparent S mineralization (Smin‐app) during the wheat growing cycle, (ii) the relationship between Smin‐app and S mineralization indicators [N mineralized in anaerobic incubation (Nan) and total and particulate organic C (TOC and POC)], and (iii) the reliability of the proposed S mineralization indicators (Nan, TOC, and POC) for diagnosing S availability alone or combined with SO42−–S content at sowing (Sini). Fourteen field experiments were conducted to evaluate grain yield in response to S fertilization. Soil samples were taken before sowing and Sini, Nan, TOC, and POC were determined. Additionally, Smin‐app was calculated in 7 out of 14 experiments through a simplified S balance. The main outcomes were: (i) Smin‐app allowed us to compare S mineralization capacity among soils and was closely related to relative wheat grain yield (R2 = 0.92), (ii) Smin‐app was related to Sini, Nan, TOC, and POC, (iii) POC was the S mineralization indicator that had the best performance for diagnosing S deficiency and its use in combination with Sini allowed for satisfactory diagnosis of S status in wheat via the equation: relative grain yield = 81.5 + (0.19 × Sini) + (1.56 × POC) (Ra2 = 0.66). Sulfur mineralization proved to be an important process for wheat S nutrition. [ABSTRACT FROM AUTHOR]

Inconsistent soybean [Glycine max (L.) Merr.] seed yield response to plant density has been previously reported. Moreover, recent economic and productive circumstances have caused interest in within-field variation of the agronomic optimal plant density (AOPD) for soybean. Thus, the objectives of this study were to: (i) determine the AOPD by yield environments (YE) and (ii) study variations in yield components (seed number and weight) related to the changes in seed yield response to plant density for soybean in North America. During 2013 and 2014, a total of 78 yield-to-plant density responses were evaluated in different regions of the United States and Canada. A soybean database evaluating multiple seeding rates ranging from 170,000 to 670,000 seeds ha-1 was collected, including final number of plants, seed yield, and its components (seed number and weight). The data was classified in YEs: low (LYE, <4 Mg ha-1), medium (MYE, 4-4.3 Mg ha-1), and high (HYE, >4.3 Mg ha-1). The main outcomes were: (i) AOPD increased by 24% from HYE to LYE, (ii) per-plant yield increased due to a decrease in plant density: HYE > MYE > LYE, and (iii) per-plant yield was mainly driven by seed number across plant densities within a YE, but both yield components influenced per-plant yield across YEs. This study presents the first attempt to investigate the seed yieldto- plant density relationship via the understanding of plant establishment and yield components and by exploring the influence of weather variables defining soybean YEs. [ABSTRACT FROM AUTHOR]

A trade-off between seed protein concentration (SPC) and yield has been reported for soybean. Therefore, assessing management practices that can nullify this trade-off is relevant to avoid further declines in SPC in the future as yield continues to increase. While the positive effect of irrigation on yield is well documented, only a few studies have assessed the impact of irrigation on SPC, showing conflicting results. The objective was to determine if the trade-off between seed yield and SPC persists when irrigation is applied and how management, soil, and weather factors influence the trade-off. We hypothesized that yield increases induced by irrigation would likely decrease SPC. Our experimental approach involved the use of producer-reported data, in-situ seed collection, and crop modeling. Yield and management data were collected from 268 soybean fields in Nebraska (USA), along with data on SPC, seed oil concentration (SOC), and seed carbohydrate concentration (SCC) determined from samples collected in each field. Field-specific phenological data were derived from model simulations. The combined data were then used to assess the effect of irrigation on seed yield and constituents as influenced by management, soil, and weather factors. On average, both seed yield (+0.86 Mg ha−1) and SPC (+3.2 g kg−1) were higher, but SOC (–2.0 g kg−1) was lower, and SCC was unaffected in irrigated versus rainfed field pairs. Yield and SPC increased simultaneously in response to irrigation in two-thirds of the fields, especially when environmental conditions did not favor seed oil synthesis (e.g. , cooler temperature and less incident solar radiation). A trade-off of higher seed yield and lower SPC occurred with irrigation in the remaining fields wherein conditions were favorable for seed oil synthesis (e.g. , warmer temperatures and greater radiation). Despite higher seed yield generated in irrigated versus rainfed fields, no concurrent reduction occurred in SPC in the majority of irrigated fields – a surprising finding that was not consistent with the general expectation that higher soybean yields typically result in yield-SPC trade-off. This study showed that irrigation-induced higher soybean yields are possible without an attendant SPC penalty when temperatures and radiation are conducive for its mitigation. We are unaware of any other yield-increasing practices – except nitrogen (N) fertilization - that do not result in a concomitant decline in SPC. A hypothesized higher N supply via soil N mineralization and/or biological N fixation in irrigated fields in this study may explain the absence of yield-protein trade-off. • There have been conflicting results about the effect of irrigation on soybean seed protein concentration • The yield-protein trade-off was assessed with producer data, in-situ seed sampling, and crop modeling • Irrigation increased both seed yield (+0.86 Mg ha−1) and protein concentration (+3.2 g kg−1) • Lower temperature and radiation nullified the yield-protein trade-off in irrigated fields • The higher N supply in irrigated fields may explain the absence of a yield-protein trade-off [ABSTRACT FROM AUTHOR]

Record grain yields and increased awareness of climate variability have more producers considering intensive (i.e., high-input) wheat (Triticum aestivum L.) management. This study investigated soft winter wheat response to several agronomic inputs across intensive and traditional (i.e., low-input) management systems. Sulfur (S) deficiency can severely limit maize (Zea mays L.) yield. This deficiency could be predicted by quantifying the S concentration (SC) in the shoot biomass (BM) and by calculating the S nutrition index (SNI = observed SC/critical SC). However, as shoot SC determination is laborious, alternative S diagnostic methods should be developed in maize. Thus, the objectives of our study were to: (i) determine and validate a critical S dilution curve, (ii) quantify the critical SNI, and (iii) explore the use of SC and chlorophyll meter reading (CMR), both determined in the uppermost developed leaf at vegetative growth stages, to predict SNI and for diagnosing S status in maize. Six field studies evaluating fertilizer S rates were executed, collecting maize shoot and uppermost developed leaf samples and determining SC, CMR, yield, and SNI parameters. The main outcomes from our study were: (i) a maize critical S dilution curve was fitted (SC = 2.13BM-0.23) and validated with an independent dataset; (ii) a critical SNI threshold of 0.79 adequately diagnosed S status at ~V6 stage; (iii) at V6, SNI was linearly related to SC (R² = 0.65) and CMR (R² = 0.85). As a result, a threshold value of 2.0 g S kg-1 for SC, 47.5 units for CMR, and 0.94 units for relative CMR can be used to successfully diagnose S deficiencies at early vegetative (~V6) maize stages. Future studies testing S diagnostic tools for maize should be performed in environments with severe S deficiency and nutrient co-limitations. [ABSTRACT FROM AUTHOR]

Wheat plants were cultivated in pots with the objective of evaluating the effect of two sulfur (S) rates (+S and −S) on (i) shoot growth, S and nitrogen (N) uptake and nitrogen use efficiency (NUE) and (ii) root growth and architecture and its relations with S and N uptake. Plant samplings were at Z39, Z51 and Z92 stages. Shoot mass and NUE were greater in +S treatment at the three stages. −S treatment increased root growth at Z39 (14% more length and 16% more tips) in comparison with +S, but the opposite occurred at Z51 (31% less area and 42% less mass). S uptake per unit root mass, area and length were greater in +S treatment at Z39 and Z51. A similar pattern was determined for nitrogen uptake (Nu) at Z39, but the opposite occurred at Z51. This indicates that Nu is mainly controlled by shoot growth and not by root growth. [ABSTRACT FROM PUBLISHER]

Legume cover crops are often considered a valuable alternative for supplying nitrogen (N) to cropping systems. However, certain pathways of N released from their residues to successor crops remain unclear. Aiming to assess N contribution and residual N from hairy vetch (Vicia villosa Roth.) cover crop in succeeding crops, we examined i) soil N availability and mineralizable-N, ii) crop yields, and iii) plant N sourcing within the soybean [ Glycine max (L.) Merrill]-wheat (Triticum aestivum L.) cropping sequence in the southeastern Argentine Pampas. Three field experiments were conducted over three seasons: E1 (2018/19), E2 (2019/20), and E3 (2020/2021) in the southeast of Buenos Aires province. The crop sequence studied was hairy vetch/soybean-wheat. Factors investigated were hairy vetch inclusion and bare fallow, and wheat N fertilizer (150 and 0 kg N ha−1). Hairy vetch aboveground dry matter and its N concentration were measured at hairy vetch termination and six times thereafter (residues) during the succeeding soybean, using the litter bag method. Soybean biomass, N concentration, and the relative abundance of ureides (RAU) as an indicator of N fraction derived from biological nitrogen fixation (BNF), were examined. Soil NO 3 --N and anaerobically incubated N (Nan) were sampled during the soybean season and at wheat sowing. At physiological maturity, soybean and wheat grain yields, along with grain N concentrations, were determined. Hairy vetch N released during soybean season ranged from 79 to 175 kg N ha−1. Soil NO 3 --N content at soybean sowing increased 5.5 kg ha−1 per Mg of hairy vetch dry matter, while Nan increased 3.6 mg kg−1 per Mg of hairy vetch dry matter. Soybean seed yields, seed N content, and N uptake showed no significant change with increased hairy vetch dry matter. Likewise, RAU at R5 decreased from 2.4 to 5.5 units (%) per Mg of hairy vetch dry matter. Concerning wheat, hairy vetch produced a slight increase in soil residual N at sowing. Only in one experiment (E1), hairy vetch dry matter led to improvements in wheat grain yield and N content. Our study outlined new insights into hairy vetch N contribution, primarily linked to increased soil N availability in the immediate soybean, the relatively higher soybean N uptake from soil compared to BNF, and the dilution of soil N contribution to wheat as second crop in the sequence. These findings support the recommendation of using hairy vetch as a predecessor for an immediate cereal or non-N fixing crops. • Nitrogen (N) dynamics were studied in a hairy vetch – soybean – wheat sequence. • Hairy vetch increased soil nitrate-N and mineralizable-N for the following soybean. • Increased hairy vetch N residues decreased soybean N fixation at the seed filling stage. • Hairy vetch neither affected subsequent soybean yields nor its total N uptake. • Hairy vetch marginally increased soil nitrate-N but did not affect mineralizable-N for wheat. [ABSTRACT FROM AUTHOR]