Subsequent Wheat Research Articles

Selecting an optimal sorghum cultivar can improve nitrogen availability and wheat yield in crop rotation.

Sorghum (Sorghum bicolor L. Moench) is a cereal crop known for its biological nitrification inhibition (BNI) capacity, a plant-mediated activity limiting nitrification pathway. The use of BNI-producing plants represents an environmentally friendly and cost-effective approach to reduce nitrogen (N) losses, such as nitrate (NO3 -) leaching and nitrous oxide (N2O) gas emissions. The present study aimed to test the effectiveness of different S. bicolor cultivars in rotation to retain ammonium (NH4 +) in soils and promote N availability for the subsequent wheat crop. A two-year field rotation was established with four sorghum cultivars followed by winter wheat (Triticum aestivum L.). Urea alone or combined with the urease inhibitor N-(n-butyl) thiophosphoric triamide was applied to promote a NH4 +-based fertilization regimes. AddingN-(n-butyl) thiophosphoric triamide maintained higher soil NH4 + content and reduced ammonia-oxidizing bacteria population during sorghum cultivation. However, the benefits of the inhibitor on sorghum growth were cultivar-dependent. Notably, the further reduction in ammonia-oxidizing bacteria abundance for sorghum Voyenn and the increased soil NH4 + content for Vilomene suggested a BNI potential for these cultivars. Importantly, the Vilomene precedent enhanced wheat yield for both fertilization regimes. Overall, the present study confirms that sorghum is a suitable catch crop and emphasizes the importance of selecting the proper sorghum cultivar to maximize the yield of the target wheat crop, at the same time as minimizing N losses. Furthermore, developing combined strategies with selected sorghum cultivars and the application of urease inhibitors enables to enhance sorghum productivity as forage, achieving added value to the rotation. © 2024 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Actinobacteria derived from soybean/corn intercropping influence the subsequent wheat

Soil legacy effects, especially soil bacterial legacy effects, influence growth, fitness and nutrient acquisition in sequential cropping systems. To date, mechanisms underlying soil bacterial legacy influences on subsequent crops remain largely unknown. In this study, we employed soybean monoculture (S), corn monoculture (C), and soybean/corn intercropping (SC) to study soil legacy effects on the growth and nutrient acquisition of wheat. In these tests, S, C and SC drove establishment of distinctive soil bacterial communities, with higher abundances of Actinobacteria and Proteobacteria taxa observed in SC plots than in S and C treatments. Variation among soil bacterial communities was associated with functional shifts in nitrogen cycling in SC treatment compared to other treatments（C and Control）. Soil legacy effects in turn may contribute to growth, nutrient acquisition and grain production in wheat crops planted in rotations. Pot assay suggest that soil microorganism of SC treatment significantly increased the plant height of wheat by 15.1 % and 18.7 %, the shoot biomass by 50.7 % and 62.7 %, the nitrogen content by 76.0 % and 94.9 %, the phosphorus content by 80.3 % and 75.9 %, and the potassium content by 64.0 % and 83.7 % by compared with C and S. Actinobacteria taxa collections further promote nutrient acquisition of wheat. Taken together, our observations from field plots and manipulation of specific bacterial taxa revealed novel soil bacterial legacy effects of previously reared crops on subsequent crops. These new insights open avenues for using soil legacy effects for positive impacts in crop rotation systems.

Soil nitrous oxide emissions from wheat-based rotations with different types of pulse crops

Production of agricultural crops with a low greenhouse gas (GHG) footprint is essential to mitigate the adverse effects of climate change. The inclusion of pulse crops in cereal-based rotations can enhance environmental quality by providing biologically fixed N and thereby reducing the amount of synthetic N fertilizer required for the crop rotation. The inclusion of pulse crop has the potential to reduce N2O emissions from the agricultural system in both the legume phase and the subsequent wheat phase of the rotation. However, long-term studies are necessary to thoroughly investigate N2O emissions from rotations with pulse crops, particularly in the semiarid region where pulse crops are frequently grown. In the present study, we evaluated cumulative N2O emissions and emission intensity during the rotation cycle. The assessment was conducted over 4 years, during two complete 2-yr cycles of an established rotation (years 9–12), under the climatological conditions of 2018–2021. Four rotations including wheat-wheat, pea-wheat, lentil-wheat, and chickpea-wheat were selected from a trial in Swift Current, Saskatchewan (semiarid prairies/Brown Chernozem). Our experiment was subjected to below normal precipitation, with interannual variations in climate and the last 2 years (2020–21) were drier than the first two years (2018–2019). Under such climate, PW and LW demonstrated to be environmentally sustainable, always exporting the highest N in grains (133 kg N ha−1 averaged across PW and LW and cycles) and consistently achieving the lowest N2O intensity (2.8 g N2O-N per kg exported N averaged across PW and LW and cycles). Continuous wheat presented inconsistent results, with a significant reduction in exported N from years 9–10 to 11–12 (the driest cycle). Because WW also promoted the highest cumulative N2O emissions, N2O intensity over the 2-yr was always the highest for WW. The CW consistently promoted the lowest N exports and was not resilient to dry soil conditions, with 23% lower exported N in years 11–12 than in years 9–10. Hence including pulse crops with pea or lentil in the rotation reduced N2O emissions and enhanced wheat yield resiliency.

N Stress Alleviation in Crops—A System Approach Analysing Residual N From Winter Crops in a Late‐Maize‐Wheat Sequence

ABSTRACTNitrogen (N) is crucial for crop production. Crop sequences with different legume participation affect N availability and therefore N fertiliser management. The study aimed to assess the inclusion of winter crops (WC) with different amounts of residues and different C:N ratios on the following: (i) the response to N fertilisation in the following late‐maize (Zea mays L.), and to carry that comparison into a subsequent wheat crop (Triticum aestivum L.), and (ii) identify soil N indicators associated with these responses. Two field experiments (E1 and E2) were conducted in the Argentinean Pampas during two growing seasons to evaluate a WC/late‐maize‐wheat sequence under no‐tillage. In each experiment, late‐maize was sown after a bare‐fallow and three WC: wheat, vetch (Vicia villosa L.) and field pea (Pisum sativum L.), where five rates of N fertilisation were evaluated. An area of late‐maize that was not fertilised with N within each previous WC was used to evaluate the response to N fertilisation in the subsequent wheat crop. Indigenous N was estimated by using N uptake in the non‐N‐fertilised treatments. Soil N indicators and C:N ratio of WC residues were evaluated as indicators of response to N fertilisation in both crops. Significant responses to N fertilisation in grain yield and N uptake were observed in late‐maize when bare‐fallow and wheat were the previous treatments in both experiments. In contrast, vetch and field pea supplied 32 and 40 kg N ha−1 in E1 and E2, respectively, and showed no response to N fertilisation, satisfying the N required by late‐maize. However, this supply was not enough to sustain the N demand of the subsequent wheat, where the response to N addition ranged from 36% to 74% when vetch and wheat were the previous WC, respectively. Only soil inorganic N indicators were associated with indigenous N supply. Moreover, the apparent net WC effect was linked to late‐maize (r2 = 0.91) and subsequent wheat (r2 = 0.67) grain yield response, which was also related to the C:N ratio of the WC residues in late‐maize and the subsequent wheat (r2 = 0.78), suggesting that mineralisation occurs when C:N ratio is below 18. Consequently, in future studies the C:N ratio of the WC residues can be included in N fertilisation recommendation schemes when late‐maize is sown as a double crop in more intensified crop sequences.

Alternative cereal crop rotations in a no‐tillage dryland under Mediterranean conditions

AbstractCereal crops are frequently rotated with broadleaf crops to achieve the benefits associated with crop diversification. However, broadleaf crops often fail in Mediterranean drylands due to their lower adaptation to drought. Alternative cereal crops such as triticale (×Triticosecale Wittmack) and oat (Avena sativa L.) can help diversify drylands in the Ebro valley, dominated by barley (Hordeum vulgare L.) and wheat (Triticum aestivum L.) cultivation. A 6‐year field experiment was conducted with five crop sequences under no‐tillage: triticale–wheat–barley (TWB), oat–wheat–barley (OWB), fallow–wheat–barley, monocrop wheat, and monocrop barley. Wheat and barley grain yield, N use efficiency, and water use efficiency responses were evaluated, and economic analyses of the whole sequences were performed. Oat increased subsequent wheat yields by 15% and barley yields by 12% (p < 0.001) compared to monocropping. Similar water and N availability at sowing suggest additional synergies in an OWB rotation (possibly pest reduction), contributing to the yield increase of both crops. However, this rotation was less profitable than a TWB rotation (p = 0.002) due to the limited adaptation of oat to Mediterranean settings. Long fallowing lacked consistent benefits in water and N availability for subsequent crops. This practice protects farmers from economic losses in low‐yielding seasons, but there is an associated opportunity cost in favorable years. The introduction of alternative cereal crops has demonstrated benefits for wheat and barley production, although greater understanding of the synergistic mechanisms involved is essential to ascertain whether resource efficiency is maintained beyond the studied timeframe.

Effect of agricultural management system (“cash crop”, “livestock” and “climate optimized”) on nitrous oxide and ammonia emissions

AbstractThe study aimed to measure soil-atmosphere N2O fluxes and their controlling factors, as well as NH3 emissions and yields for two soils (silt loam and clay loam) in three management systems over two years under subsequent wheat and maize cultivation. The management systems were characterized as follows: (1) cash crop (C) with mineral fertilizer and conventional tillage; (2) livestock (L) with biogas residue fertilization and its incorporation prior to sowing in maize and reduced tillage; and (3) climate optimized (O) with minimum tillage, 8-year crop rotation, with biogas residue fertilization, in maize without incorporation in clay loam soil or incorporation by strip-tillage prior to seeding in silt loam soil. Stable isotope ratios of N2O and mineral N were determined to identify N2O processes. Within the organically fertilized maize treatments, cumulative N2O fluxes were highest in the O-system treatments of both sites (4.0 to 9.4 kg N ha− 1 a− 1), i.e. more than twice as high as in the L-system (1.5 to 3.1 kg N ha− 1 a− 1). Below root-strip till fertilizer application did not enhance N2O fluxes. Fluxes with mineral fertilization of wheat (1.1 to 3.1 kg N ha− 1 a− 1) were not different from those with organic fertilization. Isotopic values of emitted N2O revealed that bacterial denitrification dominated most of the peak flux events, while the N2O/(N2 + N2O) ratio of denitrification was mostly between 0.1 and 0.5. It can be concluded that, contrary to the intention to lower greenhouse gas fluxes by the O-system management, the highest N2O fluxes occurred in the O-system without biogas digestate incorporation in maize. With respect to NH3 fluxes, we could confirm that the application of digestate application in growing crops without incorporation or late incorporation in fertilization before sowing induces high fluxes. The beneficial aspects of the O-system including more stable soil structure and resource conservation, are thus potentially counteracted by increased N2O and NH3 emissions.

Responses of soil aggregation and aggregate‐associated nitrogen to straw return in China: Evidence from a meta‐analysis and a pot experiment

AbstractEnhancing soil structure and soil nitrogen availability is the key to sustainable agricultural development in global cropping systems. Straw return can affect soil aggregation, but the results of recent studies on the influence of straw return on soil aggregation are not consistent, and the distribution and availability of straw‐derived nitrogen in soils are still unclear. Here, a meta‐analysis of the effects of straw return on soil aggregation was conducted based on 57 studies published in China over the past 10 years. Moreover, combined with a pot experiment, the distribution and transfer characteristics of the two main wheat (Triticum aestivum L.)‐preceding crops, corn (Zea mays L.) and soybean (Glycine max L.) straw‐derived nitrogen in the soils were studied by using the 15N‐tracer method in the main wheat‐producing areas of China. 15N‐labeled straw was introduced into soils in pots at rates of 0.3% and 0.5% of the soil dry mass and incubated 60%–70% of the field water capacity throughout the entire growth period of wheat (220 days). A meta‐analysis revealed that straw return significantly improved the mass ratio of large macro‐aggregates (LM%) and small macro‐aggregates (SM%) but significantly decreased the mass ratio of micro‐aggregates (MI%) and silt plus clay‐size particles (CS%), with mean effect sizes of 36.27%, 9.06%, −8.26%, and −21.32%, respectively. The mean weight diameter (MWD) and geometric mean diameter (GMD) also increased by 21.48% and 15.64%, respectively. Compared with SM%, LM% made a greater contribution to the stability of soil aggregates. Moreover, only LM% showed a significant positive correlation with the corresponding aggregate‐associated nitrogen content, which was an important reason for the improvement in soil nitrogen availability after straw return. The positive effect of straw return on soil aggregation was greatest when the soil pH was close to 6.5–7.5, the average annual temperature was greater than 15°C, and the average annual rainfall was close to 800–1000 mm. The results of the pot experiment revealed that the proportions of straw‐derived nitrogen in >2 mm aggregates were 1.21–1.28, 1.50–2.23, and 1.34–1.74 times greater than those in 0.25–2, 0.053–0.25, and <0.053 mm aggregates, respectively. Moreover, the proportion of straw‐derived nitrogen content of aggregates of different particle sizes showed that the proportion of straw used to reach 0.5% of the soil dry weight was greater than 0.3%, which was 1.09–1.66 times greater, and that of soybean straw was significantly greater than that of corn straw, which was 1.50–2.28 times greater. At application rates of 60 g pot−1 and 100 g pot−1 straw, the absorption of soybean straw‐derived nitrogen by wheat was 1.83 and 2.15 times greater than that of corn straw‐derived nitrogen, respectively. In conclusion, straw return effectively improved soil aggregate stability and nitrogen availability, which was closely related to the increase in soil LM%. Soybean straw can stabilize soil aggregates better than corn straw, and its straw‐derived nitrogen is an important nitrogen source for subsequent wheat crops.

Dry direct-seeded rice-wheat rotation system: Lower water and carbon footprint and higher carbon production efficiency and net ecosystem economic benefits

ContextSecuring food and energy supplies presents a significant challenge to human survival and progress. The rice-wheat rotation is one of the main food crop systems in China. However, no comprehensive assessment of the water footprint (WF), carbon footprint (CF), carbon production efficiency (CPE), and net ecosystem economic benefits (NEEB) of different rice-wheat rotation systems has been reported. ObjectiveThis study was conducted to assess the productivity, WF, CF, CPE, and NEEB of dry direct-seeded, wet direct-seeded, and transplanted rice-wheat (TR-W) rotation systems. The objective was to provide theoretical guidance for the development of clean and sustainable rice-wheat rotation production technology systems. MethodsWe used a split-plot design, with the main plots being the dry direct-seeded, wet direct-seeded, and transplanted rice planting methods, and the subplots consisting of two rice genotypes. Dry direct-seeded rice was mainly rainfed, ensuring that the soil remained relatively dry so that the soil is kept aerobic during the whole reproductive period of rice. Wet direct-seeded rice continues to keep the soil moist after sowing; the plots were maintained under a water layer of 3–10 cm following the emergence of 4.5 leaves, a condition that persisted until two weeks prior to the rice harvest. Transplanted rice was maintained under a water layer of 3–10 cm following transplanting until 2 weeks prior to the rice harvest. Subsequent to the rice harvest, the above-ground rice stubble was removed, and the ground was tilled with a rotary tiller in preparation for the subsequent wheat planting. ResultsResults demonstrated that the annual yield from the dry direct-seeded rice-wheat (DR-W) rotation system was comparable to the wet direct-seeded rice-wheat (WR-W) rotation system, while significantly lower than that of the TR-W rotation system. However, the WF of DR-W rotation system was 45.96% and 33.94% lower than that of WR-W and TR-W rotation systems, respectively, and the CF was 35.57% and 25.87% lower than that of WR-W and TR-W rotation systems, respectively. Therefore, its water and carbon production efficiencies were higher than those of WR-W and TR-W rotation systems. In addition, NEEB in DR-W and TR-W was comparable and significantly higher than that in WR-W. ConclusionsThe DR-W rotation was a promising rotation system according to the comparable annual yield, lower water and carbon footprints, higher CPE, and comparable or higher NEEB in comparison with other rice-wheat rotation systems. SignificanceWe suggest that the DR-W rotation should be promoted as the primary production mode for the rice-wheat rotation.

Residual effect of nutrient management of kharif groundnut on nutrient content-uptake and soil nutrient-microbial dynamics in subsequent wheat under organic farming

Residual effect of nutrient management of kharif groundnut on nutrient content-uptake and soil nutrient-microbial dynamics in subsequent wheat under organic farming

Residual effect of nutrient management of kharif groundnut on growth, yield attributes, yield and quality of subsequent wheat under organic farming

Residual effect of nutrient management of kharif groundnut on growth, yield attributes, yield and quality of subsequent wheat under organic farming

Nitrogen rhizodeposition from corn and soybean, and its contribution to the subsequent wheat crops

Nitrogen (N) is a key factor in the positive response of cereal crops that follow leguminous crops when compared to gramineous crops in rotations, with the nonrecyclable rhizosphere-derived N playing an important role. However, quantitative assessments of differences in the N derived from rhizodeposition (NdfR) between legumes and gramineous crops are lacking, and comparative studies on their contributions to the subsequent cereals are scarce. In this study, we conducted a meta-analysis of NdfR from leguminous and gramineous crops based on 34 observations published worldwide. In addition, pot experiments were conducted to study the differences in the NdfR amounts, distributions and subsequent effects of two major wheat (Triticum aestivum L.)-preceding crops, corn (Zea mays L.) and soybean (Glycine max L.), by the cotton wick-labelling method in the main wheat-producing areas of China. The meta-analysis results showed that the NdfR of legumes was significantly greater by 138.93% compared to gramineous crops. In our pot experiment, the NdfR values from corn and soybean were 502.32 and 944.12 mg/pot, respectively, and soybean was also significantly higher than corn, accounting for 76.91 and 84.15% of the total belowground nitrogen of the plants, respectively. Moreover, in different soil particle sizes, NdfR was mainly enriched in the large macro-aggregates (>2 mm), followed by the small macro-aggregates (2–0.25 mm). The amount and proportion of NdfR in the macro-aggregates (>0.25 mm) of soybean were 3.48 and 1.66 times higher than those of corn, respectively, indicating the high utilization potential of soybean NdfR. Regarding the N accumulation of subsequent wheat, the contribution of soybean NdfR to wheat was approximately 3 times that of corn, accounting for 8.37 and 4.04% of the total N uptake of wheat, respectively. In conclusion, soybean NdfR is superior to corn in terms of the quantity and distribution ratio of soil macro-aggregates. In future field production, legume NdfR should be included in the nitrogen pool that can be absorbed and utilized by subsequent crops, and the role and potential of leguminous plants as nitrogen source providers in crop rotation systems should be fully utilized.

Influence of organic amendments and different levels of nitrogen on production potential, economics and energetics of rice (Oryza sativa)–wheat (Triticum aestivum) cropping system

A field experiment was conducted during 2018–19 and 2019–20 at the Punjab Agricultural University, Ludhiana and Research Station, Dyal Bharang, Amritsar, to study the influence of organic amendments and nitrogen levels on rice (Oryza sativa L.)-wheat (Triticum aestivum L.) cropping system. In rice, main plot treatments were green manuring (GM), farmyard manure (FYM), poultry manure (PM) and control (NA). Nitrogen levels in sub-plots comprised control (N1), 50 kg N/ha (N2),75 kg N/ha (N3) and 100 kg N/ha (N4). In wheat, residual effect of organic amendments and nitrogen levels applied to preceding rice was evaluated. The statistically highest grain yield of rice was obtained with PM (8.29 t/ha), followed by GM (8.02 t/ha) which was at par with FYM (7.90 t/ha). The lowest rice grain yield was obtained with NA (5.16 t/ha) and its subsequent wheat crop recorded significantly higher grain yield with PM (6.14 t/ha), followed by FYM (5.88 t/ha) and GM (5.72 t/ha). Treatment N4 recorded significantly higher yield than N2 and was at par with N3. Maximum rice-equivalent yield (14.7 t/ha) was recorded with PM, while the highest energy-use efficiency of rice was recorded with green-manure (16.2) as compared to the other treatments. Treatment with the application of PM and N4 recorded significantly the highest economic parameters and system productivity for both rice and wheat crops compared to rest of the treatments.

Investigating the Impact of Tillage and Crop Rotation on the Prevalence of phlD-Carrying Pseudomonas Potentially Involved in Disease Suppression.

Winter oilseed rape (OSR) is becoming an increasingly popular crop in rotations as it provides a cash crop and reduces the incidence of take-all fungal disease (caused by Gaeumannomyces graminis) in subsequent wheat production. The exact mechanism of this inhibition of fungal pathogens is not fully understood; however, the selective recruitment of bacterial groups with the ability to suppress pathogen growth and reproduction is thought to play a role. Here we examine the effect of tillage practice on the proliferation of microbes that possess the phlD gene involved in the production of the antifungal compound 2,4-diacetylphloroglucinol (2,4-DAPG), in the rhizospheres of both winter oilseed rape and winter wheat grown in rotation over a two-year period. The results showed that conservation strip tillage led to a significantly greater phlD gene copy number, both in the soil and in the roots, of oilseed rape and wheat crops, whereas crop rotation of oilseed rape and wheat did not increase the phlD gene copy number in winter wheat.

Legume-based rotation enhances subsequent wheat yield and maintains soil carbon storage

Legume-based rotation enhances subsequent wheat yield and maintains soil carbon storage

Increasing the Efficiency of the Rice–Wheat Cropping System through Integrated Nutrient Management

The advancement of effective nutrient management strategies has been instrumental in enhancing crop productivity and economic viability. Thus, we investigated the effect of green manure and organic amendments at varying nitrogen levels in rice and their residual effect on wheat crops. A two-year research study (2018–2019 and 2019–2020) was conducted at two distinct locations: Punjab Agricultural University in Ludhiana and a Research Station in Dyal Bharang, Amritsar. The experimental design employed was a split-plot design. The main plot treatments consisted of four treatments (green manuring, farmyard manure, poultry manure, and no organic amendment (control)) and four subplot treatments (No N control, 50 kg N ha−1, 75 kg N ha−1, and 100 kg N ha−1), replicated four times in the rice crop, and its residual effect was studied in wheat. The study found that applying organic amendments at different nitrogen levels significantly increased rice–wheat productivity, growth, yield qualities, nutrient uptake, and efficiency (p < 0.05). Poultry manure increased rice grain yield more than other modifications. It significantly increased grain yield by 67.3% and 61.4% over the control in both years of the research. Poultry manure (41.9 kg, 60.0%) increased AE (kg grain kg−1 N uptake) and ANR (%) compared to control due to higher total N (177.4 kg ha−1), P (31.6 kg ha−1), and K (179.6 kg ha−1). Grain production was positively correlated with total nitrogen (N), phosphorus (P), and potassium (K) intake (r = 0.992**, 0.931**, and 0.984**, respectively). Total N uptake was positively correlated with P and K uptake (r = 0.963** and 0.991**, respectively). Poultry manure improved soil health by increasing total microbial count and alkaline phosphatase activity. In the subsequent wheat crop, rice grown with poultry manure yielded 24.3 and 24.4 percent more than no organic amendment control in rabi 2018–2019 and 2019–2020. The findings suggest that poultry manure and 100 kg N ha−1 or 75 kg N ha−1 afforded equivalent yields. This shows that even less nitrogen may be enough to boost rice and wheat yields.

Soil chemical and microbial gradients determine accumulation of root‐exuded secondary metabolites and plant–soil feedbacks in the field

AbstractIntroductionHarnessing positive plant–soil feedbacks via crop rotations is a promising strategy for sustainable agriculture. These feedbacks are often context‐dependent, and how soil heterogeneity explains this variation is unknown. Plants influence soil properties, including microbes, by exuding specialized metabolites. Benzoxazinoids, specialized metabolites released by cereals such as wheat and maize, can alter rhizosphere microbiota and performance of plants subsequently growing in the exposed soils and are thus an excellent model to study agriculturally relevant plant–soil feedbacks.Materials and MethodsTo understand local variation in soil properties on benzoxazinoid‐mediated plant–soil feedbacks, we conditioned plots with wild‐type maize and benzoxazinoid‐deficient bx1 mutants in a grid pattern across a field, and we then grew winter wheat in the following season. We determined accumulation of benzoxazinoids, root‐associated microbial communities, abiotic soil properties and wheat performance in each plot and then assessed their associations.ResultsWe detected a marked gradient in soil chemistry and microbiota across the field. This gradient resulted in significant differences in benzoxazinoid accumulation, which were explained by differential benzoxazinoid degradation rather than exudation. Benzoxazinoid exudation modulated microbial diversity in root and rhizospheres during maize growth, but not during subsequent wheat growth, while the chemical fingerprint of benzoxazinoids persisted. Averaged across the field, we did not detect feedbacks on wheat performance and defence, apart from a transient decrease in biomass during vegetative growth. Closer analysis, however, revealed significant feedbacks along the chemical and microbial gradient of the field, with effects gradually changing from negative to positive along the gradient.ConclusionOverall, this study revealed that plant–soil feedbacks differ in strength and direction within a field and that this variation can be explained by standing chemical and microbial gradients. Understanding within‐field soil heterogeneity is crucial for the future exploitation of plant–soil feedbacks in sustainable precision agriculture.

Tillage, green manuring and crop residue management impacts on crop productivity, potassium use efficiency and potassium fractions under rice-wheat system

The conventional crop production practices including intensive tillage and open field crop residue burning in world’ largest rice-wheat system (RWS) are adversely affecting crop productivity besides deteriorating natural resources and ecosystems’ sustainability. In order to improve system productivity, potassium (K) use efficiency and apparent K balance, adoption of conservation tillage in a RWS with residue management is considered highly effective. We therefore, studied the effect of wheat straw retention and green manure (GM) in rice (main plot treatment), and tillage and rice residue management in subsequent wheat (sub-plot treatments) on crop productivity, K use efficiency and its transformation amongst different fractions of variable solubility. These results revealed that rice straw retention along with GM significantly (p < 0.05) increased the rice yields by ∼5.3–6.7% and wheat yields by ∼10.2–16.9%, compared to the conventional tillage (CT) without GM. Green manuring during the intervening period (CTRW0+GM) significantly increased the rice grain K uptake by ∼36.2% than in plots with no-GM (CTRW0). However, it increased by ∼29.8% under CTRW25+GM, compared with CTRW25-GM treatment. As compared with CTRW0, CTRW0+GM significantly increased the reciprocal internal use efficiency of K of rice by 3.8 kg Mg−1 grain yield (∼29.5%). However, CTRW25+GM increased the RIUEK of rice by 3.3 kg Mg−1 grain yield (∼22.4%), compared with no-GM (CTRW25). Although, apparent K balance was net negative for CTRW25, ZTWR100 treatments, yet there was decreased K mining of 56–262 kg K ha−1 (∼11.9–61.2%) for CTRW25 and ZTWR100 over CTRW0 and ZTWR0. The increased crop yield, K uptake and K use efficiency were significantly related to K enrichment in water soluble K, exchangeable K, non-exchangeable-K, hydrochloric acid extractable-K, lattice-K and total K fractions by ∼1.3, 3.4, 18.6, 11.0 and 34.1%, respectively due to residue retention, compared with no residue. Therefore, conventional tillage with puddled transplanted rice (CTR) with wheat residue and green manure during intervening period (CTRW25+GM), and zero tillage wheat with rice residue retention (ZTWR100) were emerged as highly valuable technological options for mitigating soil degradation effects under intensive RWS for food grains in north-western India.

Effect of different rice planting methods on the water, energy and carbon footprints of subsequent wheat

The rice-wheat rotation system is an important planting system in the middle and lower reaches of the Yangtze River. Studies on the effects of different rice planting methods on the water, energy, and carbon footprints of subsequent wheat have rarely been reported. In this study, the effects of different rice cultivation practices on the water, energy, and carbon footprints of subsequent wheat were investigated among different rice-wheat rotation systems including dry direct-seeded rice (DSR)-wheat rotation, wet direct-seeded rice (WSR)-wheat rotation and transplanted rice(TPR)-wheat rotation. Results showed that the yield of wheat after DSR was 8,552 kg ha−1, which was 14.61 and 4.72% higher than the yields after WSR and TPR, respectively. In addition, the water and carbon footprints of wheat after DSR were lower than those after WSR and TPR, while its energy and carbon production efficiencies and net ecosystem economic benefits were higher than those after WSR and TPR. Notably, the use of fertilizers and fuel are the two major contributors to the high energy inputs and greenhouse gas emissions in wheat production. In summary, wheat after DSR has higher ecological and economic benefits, and we recommend that it be promoted as the preferred wheat planting model in rice-wheat rotation areas.

Peanut-based Rotation Stabilized Diazotrophic Communities and Increased Subsequent Wheat Yield.

The introduction of legumes into rotations can improve nitrogen use efficiency and crop yield; however, its microbial mechanism involved remains unclear. This study aimed to explore the temporal impact of peanut introduction on microorganisms related to nitrogen metabolism in rotation systems. In this study, the dynamics of diazotrophic communities in two crop seasons and wheat yields of two rotation systems: winter wheat - summer maize (WM) and spring peanut → winter wheat - summer maize (PWM) in the North China Plain were investigated. Our results showed that peanut introduction increased wheat yield and biomass by 11.6% (p < 0.05) and 8.9%, respectively. Lower Chao1 and Shannon indexes of the diazotrophic communities were detected in soils that sampling in June compared with those sampling in September, although no difference was found between WM and PWM. Principal co-ordinates analysis (PCoA) showed that rotation system significantly changed the diazotrophic community structures (PERMANOVA; p < 0.05). Compared with WM, the genera of Azotobacter, Skermanella, Azohydromonas, Rhodomicrobium, Azospirillum, Unclassified_f_Opitutaceae, and Unclassified_f_Rhodospirillaceae were significantly enriched (p < 0.05) in PWM. Furthermore, rotation system and sampling time significantly influenced soil properties, which significantly correlated with the top 15 genera in relative abundance. Partial least squares path modeling (PLS-PM) analysis further showed that the diazotrophic community diversity (alpha- and beta-diversity) and soil properties (pH, SOC and TN) significantly affected wheat yield. In conclusion, legume inclusion has the potential to stabilize diazotrophic community structure at the temporal scales and increase subsequent crop yield.

Potentials of legumes rotation on yield and nitrogen uptake of subsequent wheat crop in northern Ethiopia

Nitrogen has becoming the most limiting nutrient in the northern highlands of Ethiopia due to continuous cropping with application of limited external inputs. To improve soil nutrient availability, farmers have been using legumes in crop rotation. However, the roles of various legumes on subsequent wheat (Triticum aestivum) crop are unknown in northern Ethiopia. The objective of this study was to investigate impacts of legumes on yield and N uptake of subsequent wheat crop. Experiment was conducted at farmer's field with faba bean (Vicia faba L.), ‘dekeko’ field pea (Pisum sativum var. abyssinicum), field pea (Pisum sativum), lentil (Lens culinaris) and wheat (Triticum spp.) in the first season and all plots were rotated by wheat in the second season. Yield of subsequent wheat crop was recorded and N uptake was analyzed. The result revealed that grain yield and dry biomass yields of subsequent wheat crop were significantly (p < 0.05) higher in the legume-wheat rotations than in the wheat-wheat rotation. The wheat yield is increased by 2196, 1616, 1254 and 1065 kg ha−1 and the N uptake is increased by 71.4%, 51.0%, 49.2% and 29.8% in the faba bean-wheat, ‘dekeko’-wheat, field pea-wheat and lentil-wheat rotation plots compared to the wheat continuous cropping, respectively. The findings indicated that legumes improved yield and N uptake of the subsequent wheat crop. Thus, soil fertility management policy need to consider legume crop rotations as nutrient management option to improve sustainable soil fertility and yield.