Wheat-corn Rotation Research Articles

Impact of varied tillage practices and phosphorus fertilization regimes on wheat yield and grain quality parameters in a five-year corn-wheat rotation system

Choosing appropriate tillage methods and applying the right amount of chemical fertilizers are pivotal for optimizing wheat management and enhancing wheat quality. This study investigated the influence of conservation agriculture and phosphorus levels on nutrient content, yield components, and quality traits of wheat in a corn-wheat rotation. Conducted over five years in field conditions, the study employed a randomized complete block design with tillage treatments (conventional tillage, CT; minimum tillage, MT; and no tillage, NT) and phosphorus levels (no fertilizer use, P0; and 100% fertilizer recommendation, PR) as factors. Soil samples were collected during the fourth year (2021–2022). Results revealed significant impacts of tillage methods and phosphorus levels on wheat straw and grain nutrient composition, yield components, and quality traits. Conventional tillage yielded the highest values for protein content (12%), Zeleny sedimentation volume (20.33 mL), hardness index (45), water absorption (64.12%), and wet gluten content (25.83%). Additionally, phosphorus fertilizer application positively influenced protein percentage, gluten weight, and gluten index. The study highlights the potential of strategic soil management, particularly conventional tillage combined with phosphorus fertilization, to enhance wheat quality and yield. By elucidating these relationships, the findings contribute to optimizing wheat cultivation practices and advancing the development of superior wheat cultivars for baking applications.

Spatial Extraction of Wheat-Corn Rotation Areas in Sushui River Basin Based on NDVI Differences in Key Phenological Stages

Spatial Extraction of Wheat-Corn Rotation Areas in Sushui River Basin Based on NDVI Differences in Key Phenological Stages

Effects of nitrogen reduction rates on grain yield and nitrogen utilization in a wheat-maize rotation system in yellow cinnamon soil

<abstract> <p>Excessive nitrogen (N) fertilizer application severely degrades soil and contaminates the atmosphere and water. A 2-year field experiment was conducted to investigate the effects of different N fertilizer strategies on wheat-summer corn rotation systems in yellow-brown soil areas. The experiment consisted of seven treatments: no N fertilization (CK), conventional fertilization (FP), optimized fertilization (CF), reduced N rates of 10% (90% FP), 20% (80% FP), 30% (70% FP), and a combination of controlled release with conventional urea at 7:3 ratio (CRU). The results indicate that under the condition of 80% FP, both CF and CRU treatments can increase the yield of wheat and corn for two consecutive years. Compared with FP treatment, the wheat yield of CF and CRU treatments increased by 3.62–2.57% and maize yield by 3.53–1.85% with N fertilizer recovery rate (NRE) of crops by 46.2–37.8%. The agronomic N use efficiency (aNUE) under CF treatment increased by 35.4–37.7%, followed by CRU, which increased by 30.5–33.9%. Moreover, compared with FP treatment, both CF and CRU treatment increased the content of organic matter (OM), total N (TN), and hydrolyzed N (HN) in the topsoil layer, and 70% FP treatment significantly reduced the HN content. Both CF and CRU treatments significantly increased the NO<sub>3</sub> concentrations in the 0–20 cm soil depth during the wheat and maize season at maturity stages and decreased the residual inorganic N below the plow layer (40–60 cm). During the corn season, the CF and CRU treatments significantly reduced the NO<sub>3</sub> concentration in the 40–60 cm soil layer from seedling to jointing. Considering various factors, CRU treatment under 80% FP conditions would be the best fertilization measure for wheat-corn rotation in yellow-brown soil areas.</p> </abstract>

Legume cover crop as a primary nitrogen source in an organic crop rotation in Ontario, Canada: impacts on corn, soybean and winter wheat yields

This study presents results from the first 5 years of an organic cropping trial in Ontario, Canada, where legume cover crops were the primary nitrogen source in a soybean-winter wheat/cover crop-corn rotation. Treatments included cover crop termination using moldboard plow (MP) or chisel plow (CP), a no-cover crop control under conventional production (CK-C), and four cover crops including summer-seeded crimson clover (CC, Trifolium incarnatum L.), summer-seeded hairy vetch (HV, Vicia villosa L. Roth), summer-seeded red clover (RCss, Trifolium pratense L.), and frost-seeded red clover (RCfs). Summer-seeding occurred after wheat harvest (July–August), and frost-seeding occurred in early spring (March–April). At cover crop termination, average aboveground cover crop biomass ranged from 5.9 to 8.1 Mg ha−1, while accumulated biomass nitrogen ranged from 155 to 193 kg ha−1. Corn grain yields were 11.6 Mg ha−1 for MP and 10.2 Mg ha−1 for CP tillage-termination method; and 13.3 Mg ha−1 for CK-C, 10.9 Mg ha−1 for RCfs, 10.6 Mg ha−1 for HV, 10.2 Mg ha−1 for CC, and 9.5 Mg ha−1 for RCss. Organic winter wheat yields were nitrogen-limited, averaging 27% lower than CK-C. Winter wheat yields were 10–15% lower in the RCfs than in other summer-seeded cover crop treatments. Soybean yields were largely unaffected by the treatments. It was concluded that summer-seeded legume cover crops are an effective primary nitrogen source for corn, but not as effective for the winter wheat phase of the soybean-winter wheat-corn rotation.

Optimizing Phosphorus Fertilizer Use on the Loess Plateau: Impact on Soil Properties and Crop Production Efficiency

Various phosphorus (P) fertilizers are commonly utilized in agricultural production on the Loess Plateau. However, there exists a widespread issue of improper matching between P fertilizers, crop types, and soil types. This study proposes a scientifically based approach to managing phosphate fertilizer through a matching experiment. A field experiment was conducted to investigate the effects of different P fertilizers on soil P profiles in a wheat–corn rotation between October 2017 and September 2021. The experiment adopted a randomized block design. P fertilizer was applied as a basal fertilizer at rates of 115 kg P2O5 ha−1 during the wheat season and 90 kg P2O5 ha−1 during the maize season. Nitrogen (N) fertilizer application rates were 120 kg N ha−1 for wheat and 180 kg N ha−1 for maize. N fertilizer was divided into two applications, with 60% applied at pre-planting and 40% at the jointing stage of wheat or the V12 stage of maize. P fertilizer variants utilized in the study included ammonium dihydrogen, ammonium phosphate, calcium-magnesia phosphate fertilizer, calcium superphosphate, and ammonium polyphosphate. The transformation process of phosphate was examined, revealing that the commonly considered dominant diammonium phosphate fertilizer was not the optimal choice in this production system. Ammonium polyphosphate, calcium superphosphate, and ammonium dihydrogen were deemed more suitable for application in Loess soil. Furthermore, an analysis was conducted on the relationship between P fractions, soil properties, and soil Olsen-P. This research emphasizes the significance of strategic phosphate fertilizer use in agriculture to ensure efficient production and to help address the global P scarcity.

Linking soil organic carbon mineralization to soil physicochemical properties and bacterial alpha diversity at different depths following land use changes

BackgroundAnthropogenic land use changes (LUCs) impart intensifying impacts on soil organic carbon (SOC) turnover, leading to uncertainty concerning SOC mineralization patterns and determining whether soils act as “source” or “sink” in the global carbon budget. Therefore, understanding the SOC mineralization characteristics of different LUC patterns and their potential influencing factors is crucial. An indoor incubation experiment was conducted to study the SOC mineralization patterns and their relevance to soil physicochemical properties, soil enzyme activity, SOC fractions, and bacterial alpha diversity. The soils were collected from two layers of five typical LUC patterns in Yellow Sea Forest Park, including four that were converted from wheat–corn rotation systems [a gingko plantation (G), a metasequoia plantation (M), a gingko–wheat–corn agroforestry system (GW), and a gingko–metasequoia system (GM)] and a traditional wheat–corn system (W).ResultsLUCs had significant and diverse impacts on the SOC content and SOC fraction contents and on soil enzyme activity. The cumulative SOC mineralization was significantly higher in the M systen than in the W and GW systems at 0–20 cm depth and higher in the G system than in the GW system at 20–40 cm depth after 60-day incubation. The mineralization ratio was highest in the W system and lowest in the GW system. The soil pH and bulk density had a significant negative correlation with the cumulative SOC mineralization, while the soil bacterial Shannon index had a significant positive correlation with cumulative SOC mineralization. Multiple stepwise linear regression analysis showed that the SOC mineralization potential was dominantly explained by the bacterial Shannon index and operational taxonomic units (OTUs). The GW system had lower potentially mineralizable SOC and higher SOC stability. Additionally, the incubation time and cumulative SOC mineralization were well fitted by the first-order kinetic equation.ConclusionsLUCs significantly changed SOC mineralization characteristics and the results highlighted the important roles of the bacterial community in soil carbon cycling, which contributes to the fundamental understanding of SOC turnover regulation.

Agricultural and municipal organic waste amendments to increase soil organic carbon: How much, how often, and to what end?

AbstractA new version of the Century ecosystem model, modified to better represent chemically and physically recalcitrant organic amendments by allowing the addition of organic waste products (OWP) as a mixture of plant material and surface slow soil organic matter (SOM) controlled by the Indicator of Residual Organic Carbon (IROC), and field observations from a 16‐year wheat corn rotation experiment near Paris, France, were used to assess the long‐term impacts of applying agricultural and municipal organic waste products (OWP) on soil carbon (C) sequestration, grain C and nutrient content, and soil nutrient status. Sixteen years of observed grain C, nitrogen (N), phosphorus (P), and potassium (K) and soil C and nutrient data were used to calibrate and validate the performance of IROC‐Century. A suite of future management scenarios, simulated using this calibrated model, explored multiple frequencies of applications of OWP and fertilizer to evaluate their long‐term impacts on grain C and nutrient content, soil C sequestration, and NO3− leaching. The model effectively simulated the impact of biennial additions of four OWP types on soil C, N, P, and K during the 16‐year experiment. Measured and simulated OWP +fertilizer resulted in higher soil C (highest for well‐decomposed [55%] vs. less‐decomposed [37%] OWP) and N content, while total soil accumulation of N, P, and K was determined by the content of the OWP, regardless of IROC, and OWP greatly reduced the need to add chemical fertilizer while increasing crop production and N, P, and K uptake by the crop. Simulation scenarios using IROC‐Century for future management suggest that the optimal cropping management system to maintain high corn and wheat production and reduce NO3− leaching is to apply OWP biennially for 12 years along with fertilizer and then reduce OWP to every fourth year while continuing to add fertilizer to the wheat crop only. However, reducing the number of OWP additions in these scenarios did decrease the rate of soil carbon sequestration.

Characterization of the responses of soil micro-organisms to azoxystrobin and the residue dynamics of azoxystrobin in wheat–corn rotation fields over two years

Azoxystrobin, a high-efficiency and broad-spectrum strobilurin fungicide, has been widely used in global agricultural production. However, the effects of azoxystrobin on soil micro-organisms have scarcely been studied, and relevant experiments are usually conducted under laboratory conditions using active ingredient. Therefore, the effects of azoxystrobin on soil micro-organisms when applied to actual farmland are unknown. We sought to address this knowledge gap in this study, where we studied the effects of azoxystrobin on soil micro-organisms in a wheat–corn rotation field over two years. The results indicate that after two years of azoxystrobin application the activities of soil enzymes were inhibited, and the abundance of functional genes related to the nitrogen and carbon cycle were inhibited, which change the abundance of soil microbial bacteria of genera. As a consequence, the soil nitrogen and carbon cycles were disturbed. In addition, azoxystrobin inhibited the abundance of functional bacteria related to organic pollutant degradation and soil metabolism, where the rate of azoxystrobin degradation diminished over time. Moreover, azoxystrobin significantly inhibited the soil-culturable microbial population. The integrated biomarker response (IBR) indicated that the soil-culturable microbial population can be used as a sensitive indicator of the effect of azoxystrobin on soil micro-organisms. The final levels of azoxystrobin residues measured in grains were less than 0.004 mg/kg, lower than the maximum residue limits in European Union and China. The results of this study provide a basis for suggestions regarding the appropriate use of azoxystrobin in addition to support for elucidating the interaction between biological macromolecules and pollutants.

N2O emissions from soils under short-term straw return in a wheat-corn rotation system are associated with changes in the abundance of functional microbes

Straw return is an effective conservation tillage measure that improves soil properties, increases crop yields, and is an efficient means of reusing agrobioenergy by-products. Straw return has been shown to affect nitrogen (N) cycling and related functional microbes in agricultural soils. However, the relationship between nitrous oxide (N2O) emissions and N-related functional genes under different straw return strategies in wheat-corn double cropping systems remains elusive. Here, we conducted a short-term field study to investigate the response of N2O emissions driven by N cycling functional genes (bacterial and archaeal amoA genes and nirS, nirK, and nosZ genes) to different straw return patterns in a wheat-corn double cropping system in the North China Plain. Three treatments were established, namely, both wheat and corn straw return (CWSR), only wheat straw mulch return (WSR), and no straw return (NSR). Over the wheat-corn season, the total N2O emissions significantly increased by 31.74% and 12.37% in CWSR and WSR-treated soils, respectively. Straw return increased nitrifying and denitrifying functional gene abundances, thus stimulating N2O emissions. Correlation analysis showed that AOA (r = 0.262, p < 0.05) and AOB (r = 0.703, p < 0.01) were strongly and positively correlated with NO3−-N concentrations, indicating that AOA and AOB were involved in nitrification under straw return. Both nirS (r = 0.287, p < 0.05) and nirK genes (r = 0.252, p < 0.05) were positively correlated with N2O emissions, while nosZ genes (r = −0.266, p < 0.05) were negatively correlated with N2O emissions. Structural equation model (SEM) analysis further revealed that straw return indirectly affected N2O emissions by influencing the abundances of AOB-amoA (r = 0.324, p < 0.05), nirK (r = 0.417, p < 0.05), and nosZ (r = −0.388, p < 0.001) genes. Overall, short-term straw return increased N2O production in a wheat-corn double cropping system, mainly through increased AOB-amoA and nirK gene abundance, which stimulated N2O production, and reduced nosZ gene abundance, which inhibited N2O reduction.

Effects of row spacing on soil nitrogen availability, wheat morpho-physiological traits and radiation use efficiency

Optimizing row spacing is an important measure to exploit the full yield potential, achieve a continuous increase in wheat yield and green development without increasing input. The objective of this study was to compare the effects of wide–narrow row spacing pattern (12 cm-12 cm-12 cm-24 cm, R1) and conventional uniform row spacing mode (20 cm, CK; 12 cm. R2) on nitrogen (N) availability in soil, canopy structure, photosynthetic characteristics, radiation use efficiency (RUE) and yield. The results showed that R1 increased the relative abundance of ammonia-oxidizing bacteria and ammonia-oxidizing archaea in the rhizosphere compared to CK. Nitrate in soils treated R1 at post-anthesis and nitrogen use efficiency of the plant were 59.92% and 27.01% higher than those treated with CK, respectively. Above-ground growth of wheat showed that R1 increased leaf area index by 27.42%, specific leaf weight by 22.67% and leaf photosynthetic rate by 8.86%, respectively compared to CK. R2 had similar availability of N and plant growth as CK. Moreover, the ability of the plant to allocate more nitrogen to grains was enhanced at post-anthesis with R1 than it with CK and R2, which greatly improved the RUE by 10.13% and 2.27%. As the result, the yield for R1 increased by 27.54% and 21.46%, respectively, compared to CK and R2. Therefore, using wide–narrow row spacing pattern (R1) is a practically and environmentally feasible approach for wheat production without extra input in the straw-returning wheat-corn rotation system.

Modeling Adaptive Strategies on Maintaining Wheat-Corn Production and Reducing Net Greenhouse Gas Emissions under Climate Change

Climate change has posed serious challenges to food production and sustainable development. We evaluated crop yields, N2O emissions, and soil organic carbon (SOC) in a typical wheat–corn rotation system field on the North China Plain on a 50-year scale using the Denitrification–Decomposition (DNDC) model and proposed adaptive strategies for each climate scenarios. The study showed a good consistency between observations and simulations (R2 &gt; 0.95 and nRMSE &lt; 30%). Among the twelve climate scenarios, we explored ten management practices under four climate scenarios (3 °C temperature change: P/T−3 and P/T+3; 30% precipitation change: 0.7P/T and 1.3P/T), which have a significant impact on crop yields and the net greenhouse effect. The results revealed that changing the crop planting time (CP) and using cold-resistant (CR) varieties could reduce the net greenhouse effect by more than 1/4 without sacrificing crop yields under P/T−3. Straw return (SR) minimized the negative impact on yields and the environment under P/T+3. Fertigation (FG) and Drought-Resistant (DR) varieties reduced the net greenhouse effect by more than 8.34% and maintained yields under 0.7P/T. SR was most beneficial to carbon sequestration, and yields were increased by 3.87% under 1.3P/T. Multiple adaptive strategies should be implemented to balance yields and reduce the environmental burden under future climate change.

Soil organic carbon fractions comparison after 40-year long-term fertilisation in a wheat-corn rotation field

Several experimental methods have been developed to fractionate soil organic carbon (SOC) into functional sub-pools. However, which fractions had the potential to better reflect the SOC dynamics responding to fertilisation are still under discussion. Thus, we compared different SOC fractions (microbial biomass carbon, MBC; dissolved organic carbon, DOC; permanganate-oxidisable carbon, POXC; particle organic carbon, POC, and aggregation organic carbon fractions) and the soil respiration rate in a wheat-corn rotation field after 40 years of manure and N fertilisation in North China to search for the most sensitive SOC fractions to fertilisation. Manure increased the organic carbon (OC) contents of all the soil fractions (26.5 to 362.8%) and the POC (18.0 to 43.7%) and macro-aggregation percentages (3.0 to 4.4%), which indicated an increasing physical-protected aggregated OC fraction. N fertilisation alone slightly increased the OC contents of all the soil fractions and DOC percentage, but decreased the macro-aggregation OC percentage, which suggests the increasing possibility that the SOC is exposed to microbial communities causing a decreasing aggregation formation. However, when a high level of both the manure and N fertiliser were applied, the excessive N in the soil stimulates the soil microbial activity and decreases the SOC content comparing it to the same level of the manure fertiliser addition.

Crop residues in corn-wheat rotation in a semi-arid region increase CO2 efflux under conventional tillage but not in a no-tillage system

Appropriate management of crop residue plays a key role in mitigating greenhouse gas emissions. However, it has been inadequately implemented in general agricultural management practices. In a field investigation using static chambers, we evaluated the effects of crop residue at three different rates - 100 % (R100), 50 % (R50), and residue removal (R0) - on carbon dioxide (CO2) efflux. The field study was conducted in corn-wheat rotation under conventional (CT) and no-tillage (NT) systems in a semi-arid region. The main results showed that CO2 efflux was positively correlated with higher soil temperature (0.43–0.79) and microbial biomass carbon (0.66–0.89). The crop residue treatments affected these traits. A strong positive relationship between CO2 efflux and the crop residue (R2 = 0.96, CT and R2 = 0.9 for NT) was observed. In the CT system, significant increases were detected among residue rates on cumulative CO2 efflux, where R100 and R50 resulted in 36 % and 25 % higher cumulative CO2 efflux, respectively, than R0. In contrast, there was no significant difference in cumulative CO2 efflux among the crop residue retention (R100 and R50) and removal (R0) treatments under the NT system. Our study revealed that crop residue retention led to increased CO2 efflux under the CT system in semi-arid conditions during the first year of application, while under the NT system, CO2 efflux was not impacted by crop residue. Our results indicate that there is considerable potential for improving soil management practices in the context of soil degradation, climate change, increasing crop productivity, and carbon (C) sequestration.

Synthesis, Herbicidal Activity, Crop Safety and Soil Degradation of Pyrimidine- and Triazine-Substituted Chlorsulfuron Derivatives.

Chlrosulfuron, a classical sulfonylurea herbicide that exhibits good safety for wheat but causes a certain degree of damage to subsequent corn in a wheat–corn rotation mode, has been suspended field application in China since 2014. Our previous study found that diethylamino-substituted chlorsulfuron derivatives accelerated the degradation rate in soil. In order to obtain sulfonylurea herbicides with good crop safety for both wheat and corn, while maintaining high herbicidal activities, a series of pyrimidine- and triazine-based diethylamino-substituted chlorsulfuron derivatives (W102–W111) were systematically evaluated. The structures of the synthesized compounds were confirmed with 1H NMR, 13C NMR, and HRMS. The preliminary biological assay results indicate that the 4,6-disubstituted pyrimidine and triazine derivatives could maintain high herbicidal activity. It was found that the synthesized compounds could accelerate degradation rates, both in acidic and alkaline soil. Especially, in alkaline soil, the degradation rate of the target compounds accelerated more than 22-fold compared to chlorsulfuron. Moreover, most chlorsulfuron analogs exhibited good crop safety for both wheat and corn at high dosages. This study provided a reference for the further design of new sulfonylurea herbicides with high herbicidal activity, fast degradation rates, and high crop safety.

Effects of straw mulching on predatory myxobacterial communities in different soil aggregates under wheat-corn rotation.

Crop straw mulching is an important organic supplement in sustainable agriculture; however, the effect of increased organic matter on the diversity of micropredators such as myxobacteria and the correlation between myxobacteria and microorganisms have been little explored. In the current investigation, high-throughput sequencing was performed to analyze the myxobacterial community composition in a wheat-corn rotation experimental field with 6-year straw mulching and fertilization treatments. The results reveal no significant influence of straw mulch application on myxobacterial α-diversity (P < 0.05). NMDS (nonmetric multidimensional scaling) and perMANOVA results indicate the significant influence of straw mulching application on myxobacterial community composition (P < 0.05), and several groups, including Haliangiaceae, Polyangiaceae, and Archangiaceae, also varied in soil aggregates. RDA (redundancy analysis) results show that TOC (total organic carbon) was the most important factor affecting the myxobacterial community structure. In addition, RDA and random forest analysis results show the contribution of myxobacterial community structure to soil bacterial community α- and β-diversity, especially in the 0.25-1mm and < 0.25mm soil aggregate fractions. In conclusion, we suggest that the variation in myxobacterial community structure may be a driver of bacterial α- and β-diversity in soil microhabitats and might be a cause of soil microbial community changes. Our results are fruitful for finding more efficient ways to use straw from waste for the betterment of sustainable agriculture by analyzing changes in myxobacterial community structure.

Soil Nitrous Oxide Emissions Following Crop Residues Management in Corn-Wheat Rotation Under Conventional and No-Tillage Systems

Agricultural activity is the major anthropogenic source of nitrous oxide (N2O) emissions from terrestrial ecosystems. Conservation agriculture including crop residue management can play a key role in enhancing soil resilience to climate change and mitigating N2O emissions. We investigated the effects of crop residue rates, including 100 % (R100), 50 % (R50), and residue removal (R0), on N2O emissions in corn-wheat rotation under conventional (CT) and no-tillage (NT) systems. The key factors evaluated affecting N2O emissions included soil temperature, soil moisture, soil ammonium, and soil nitrate concentrations. Results showed that the N2O emissions increased with the increasing rate of residue under both CT and NT systems. Both R100 and R50 significantly ( p &lt; .05) increased the N2O emissions compared to R0 during the annual rotation cycle. Soil moisture and mineral nitrogen (ammonium and nitrate) were the main driving factors that stimulated N2O emission in both CT and NT systems. In the NT and CT systems, cumulative N2O emissions showed a significant increase with R50 (+75.5 % in NT, +36.5 % in CT) and R100 (+134 % in NT, +40 % in CT) as compared to R0. Furthermore, no significant differences were found between R100 and R50 in the CT system, while in the NT system significant increases were observed for R100 compared to R50. Overall, our study justified as a first approach only during the first year that crop residue removal led to decreased N2O emissions under semi-arid conditions. However, due to the deteriorating impact of crop residue removal on crop productivity and soil C sequestration, this management method cannot be considered a sustainable agronomic practice. We suggest long-term studies to determine the appropriate rate of postharvest crop residue to achieve less N2O emissions and climate-friendly agricultural practices.

Nutrient availability affected by silicate and Azospirillum brasilense application in corn–wheat rotation

AbstractThe interactive effectof silicon (Si) application on soil fertility is poorly understood when inoculation with Azospirillum brasilense is performed. This research determined if Si application and A. brasilense inoculation to corn (Zea mays L.) and wheat (Triticum aestivum L.) has agronomic benefits on soil nutrient concentration and grain yield. Treatments were tested under a no‐till system in a Rhodic Haplustox in a full factorial design with four replicates and comprised (a) two soil amendment sources—calcium (Ca) and magnesium (Mg) silicate and dolomitic limestone; (b) with and without seed inoculation with A. brasilense; and (c) five sampling dates collected during two corn–wheat crop rotations (2015–2017). Calcium and Mg silicate application was effective at decreasing soil hydrogen + aluminum (H+Al) and Al content and increasing soil pH, sum of bases, and base saturation. However, silicate changed soil nutrient availability, reduced cation exchange capacity, phosphorus (P) and Mg content and did not significantly affect (p &gt; .05) corn and wheat grain yield. Inoculation reduced Al toxicity, with lower H+Al and Al contents, and increased K content, leading to a greater pH and base saturation after four cropping seasons. Inoculation increased corn and wheat grain yield by 8.2 and 8.3%, respectively. Application of Ca and Mg silicate was more effective than limestone as a liming agent but could result in decreased availability of certain nutrients in soil. Inoculation with A. brasilense could be an important management practice to maintain adequate Si content in soil when limestone is applied. However, with silicate application, A. brasilense could increase Si depletion in soil.

Blended controlled-release nitrogen fertilizer with straw returning improved soil nitrogen availability, soil microbial community, and root morphology of wheat

Microbial activities and nitrogen (N) availability in soil directly affect root morphology and consequently crop yield. These relationships are even more critical at the filling stage of wheat due to the grain formation. The objective of this study was to compare effects of blended controlled-release N fertilizer (CRFS) and conventional urea (BBFS) on soil microflora, soil N content, and root growth of wheat at the filling stage in a field with straw return for seven years. The method of 16 s rRNA and ITS high-throughput sequencing was used to probe soil microbial status, and the in-situ root scanner was used for in-situ observation and monitoring of wheat root morphology during two growing seasons. The results showed that CRFS increased the relative abundance of Penicillium and Aspergillus fungal genera and reduced the operational taxonomic unit of nitrifying bacteria of the genus Nitrospira compared to BBFS treatment. Nitrate, ammonium, total N, and organic matter in soils treated CRFS were 15.8 %, 10 %, 7.5 %, and 11.6 % higher than these in soils treated with BBFS, respectively, while the total root length, root surface area, and root volume from CRFS treatment were 57.6%, 48.8 %, and 54.1 % higher than these from BBFS, respectively. Above-ground growth of wheat showed that CRFS increased plant height by 5.8–12.6 %, net photosynthetic rate by 13.5–22.2 %, N content of stems and spikes by 10.0 % and 64.1 %, respectively compared to BBFS. Wheat yield and economic efficiency were increased by 9.9–46.8 %, 11.6–41.7 %, respectively with CRFS treatments than these with BBFS treatments. Wheat received reduced application rate (2/3) of CRFS had similar availability of N and plant growth as the full rate of BBFS. Therefore, using blended controlled-release N fertilizer is a practically and environmentally feasible approach for wheat production in the straw retuning wheat-corn rotation system.

Rotation and Fertilization Effects on Soil Quality and Yields in a Long Term Field Experiment

Understanding the complex relationships among soil quality, crop productivity, and management practices would help to develop more sustainable agricultural production systems. In this study, we investigated the combined effects of crop rotations and fertilization treatments on soil quality and crop yield in a long term (about 50 years) field experiment. Crop rotations included continuous corn (Zea mays L.), a 2 year corn-wheat (Triticum aestivum L.) rotation, and a 9 year corn-wheat-corn-wheat-corn-wheat-alfalfa-alfalfa-alfalfa (Medicago sativa L.) rotation. Fertilization treatments included control, mineral fertilization with urea and triple superphosphate, and amendment with cattle manure. Crop rotations and fertilization treatments were combined in a factorial experimental design with two replications for each rotation and six replications for each fertilization treatment. The continuous corn and the corn-wheat rotations had negative effects on the main soil quality indicators considered (carbon (C) and nitrogen (N) pools, microbial biomass and activity). On the contrary, the 9 year rotation had positive effects on soil organic carbon (+24%) and total nitrogen (+23%) but resulted in impoverished available P (−5%). Positive effects on soil microbial biomass (+37% of microbial biomass C and +23% of microbial biomass N) and activity (+19%) were also observed. Soil amendment with manure built up soil organic carbon (+13%), increased nutrient content (+31% of extractable C and +19% of extractable N), including that of available P (+47%), and stimulated microbial growth (+34%) and activity (+8%). As compared to manure, mineral fertilization increased the soil nutrient content to a lesser extent. This study showed that the combined use of rotations, including legume forage crops, and soil amendment with manure may help preserve soil quality and crop productivity in the long term.

Response of soil N2O emission and nitrogen utilization to organic matter in the wheat and maize rotation system

The appropriate nitrogen (N) fertilizer regulator could increase N utilization of crops and reduce N losses in the North China Plain. We investigated the effects of reduced inorganic-N rate combined with an organic fertilizer on nitrous oxide (N2O) emissions in winter wheat and summer maize rotation system. Simultaneously studied the effect of different treatments on N use efficiency (NUE), N balance and net income. After reducing the amount of nitrogen fertilizer in the wheat-corn rotation system, the results showed that the cumulative emission of soil N2O from the RN40% + HOM [40% of RN (recommended inorganic-N rate) with homemade organic matter] treatment was 41.0% lower than that of the RN treatment. In addition, the N production efficiency, agronomic efficiency, and apparent utilization were significantly increased by 50.2%, 72.4% and 19.5% than RN, respectively. The use of RN40% + HOM resulted in 22.0 and 30.1% lower soil N residual and N losses as compared with RN. After adding organic substances, soil N2O cumulative emission of RN40% + HOM treatment decreased by 20.9% than that of the HAN (zinc and humic acid urea at the same inorganic-N rate of RN) treatment. The N production efficiency, N agronomic efficiency and NUE of RN40% + HOM treatment were 36.6%, 40.9% and 15.3% higher than HAN’s. Moreover, soil residual and apparent loss N were 23.3% and 18.0% less than HAN’s. The RN40% + HOM treatment appears to be the most effective as a fertilizer control method where it reduced N fertilizer input and its loss to the environment and provided the highest grain yield.