Wheat-maize Rotation Research Articles

Straw return counteracts the negative effects of warming on microbial community and soil multifunctionality

Climate warming is one of the most serious threats to soil biodiversity and ecosystem stability. Straw return has been extensively recommended as an environmentally friendly management to increase soil health and agricultural productivity. However, little is known about their interactive effects on microbial communities and soil functioning. We investigated the effects of soil warming, straw return, and their interactions on soil microbial communities, functional genes, enzyme activities related to C, N and P cycling, and multifunctionality in a two-factorial experiment in a wheat-maize rotation system. Soil warming decreased fungal diversity (by 20%) and functional genes associated with organic matter decomposition, N fixation, nitrification, denitrification, and organic P mineralization compared with ambient temperature. Soil multifunctionality mediated by enzyme activities were reduced under warming because of lower soil moisture, nutrient availability, and root-derived labile organic matter inputs. The close relationships of microbial diversity and functional genes with soil multifunctionality highlighted the importance of soil biodiversity in maintaining agroecosystem functioning related to nutrient cycling. Under soil warming and ambient temperature, straw return resulted in higher bacterial diversity (by 3.6%) and microbial functional genes abundances of C, N and P cycling compared to straw removal, and consequently raised soil multifunctionality. This was primarily because straw buffered soil temperature amplitude and moisture variation, as well as the additional nutrient supply within the added straw. Overall, straw return created favorable habitats for microorganisms, and thereby mitigated the adverse effects of warming on microbial communities and soil functionality. Our study provided the possibility to increase soil biodiversity and further ecosystem services related to organic matter decomposition and nutrient turnover by straw addition, especially under climate warming.

Economics of Subsistence Farming: A Comparative Analysis of Paddy-wheat and Maize-wheat Rotation Cropping System in Himachal Pradesh

Background: Marginalisation of Indian agriculture, due to increase in marginal and small agricultural households, brings the focus back on subsistence agriculture. Among other things, understanding the economics of subsistence agriculture will go a long way in making its practice viable by making sure the help that these subsistence farmers need are provided. Therefore, the present study attempts to study the economics of paddy-wheat and maize-wheat rotation cropping system practiced by subsistence farmers of Himachal Pradesh whose agriculture sector is known for its diversification towards high value crops. Methods: The study has used survey data collected from 60 randomly selected households from Rait block of district Kangra, Himachal Pradesh. 30 households practicing paddy-wheat rotating cultivation are selected from Boh and Drini village and 30 households doing Maize-Wheat rotating cultivation are from Machhlini, Panjol, Khridi, Rulede and Lahri village. The study is based on primary data which has been collected through a pre-tested schedule. Using the primary data, we have brought out factors other than self-consumption needs that determines choice between two farming systems and also two group of farmers are compared in terms of productivity, cost of cultivation and net returns from cultivation. Result: Our study found that irrigation facilities play an important role in the choice between the two cropping systems. Return from cultivation is negative for both groups of farmers if imputed value of family labour is included. Performance of paddy-wheat farmers is significantly better than maize-wheat farmers in economic terms in the study area.

Ammonia loss potential and mitigation options in a wheat-maize rotation system in the North China Plain: A data synthesis and field evaluation

The North China Plain (NCP) is an intensive agricultural area and ammonia (NH3) emission hotspot in China. Urgent mitigation actions are needed to reduce its environmental impact. A field trial was conducted, and results combined with a synthesis of existing data to assess the NH3 loss and mitigation potentials in a wheat-maize double-crop rotation, a dominant crop production system in the NCP. Ammonia volatilization losses from N fertilizer applied to summer maize and winter wheat were 9.1% and 5.0%, respectively, based on the data synthesis, and were significantly affected by fertilizer application method and N fertilizer type. From the field trial, optimized reduction in N application rate, compared with conventional practice, had great efficiency for NH3 mitigation. Despite their high NH3 reduction potential, the higher input costs associated with the use of controlled-release fertilizers, replacement of urea with calcium ammonium nitrate or inclusion of double inhibitors (urease and nitrification inhibitors) with urea limited their applicability from an economic perspective. The inclusion of a urease inhibitor with urea achieved over 70% reduction in NH3 emission and also gave a significant improvement in grain yield, net income and N use efficiency. Future adoption of NH3 mitigation options in the NCP should focus on establishing a reduction target and consider the cost-benefits of simultaneous implementation of multiple mitigation techniques.

Effect of Crop Rotation on Fusarium Mycotoxins and Fusarium Species in Cereals in Sichuan Province (China).

The present study was performed to evaluate the effect of crop rotation on Fusarium mycotoxins and species in cereals in Sichuan Province. A total of 311 cereal samples were randomly collected and analyzed from 2018 to 2019 in Sichuan Province. The results of mycotoxin analysis showed that the major trichothecene mycotoxins in Sichuan Province were nivalenol (NIV) and deoxynivalenol (DON), and the mean concentration of total trichothecenes (including NIV, fusarenone X [4ANIV], DON, 3-acetyldeoxynivalenol [3ADON], and 15-acetyldeoxynivalenol [15ADON]) in wheat was significantly higher than that in maize and rice. The concentration of total trichothecenes in the succeeding crops was significantly higher than that in the previous crops. In addition, wheat grown after maize had reduced incidence and concentration of trichothecene mycotoxins compared with that grown after rice, and ratooning rice grown after rice had increased incidence and concentration of trichothecene mycotoxins. Our data indicated that Fusarium asiaticum with the NIV chemotype was predominant in wheat and rice samples, while the number of the NIV chemotypes of F. asiaticum and Fusarium meridionale and the 15ADON chemotype of Fusarium graminearum in maize were almost the same. Although the composition of Fusarium species was affected by crop rotations, there were no differences when comparing the same crop rotation except for the maize-wheat rotation. Moreover, the same species and chemotype of Fusarium strains originated from different crops in various rotations, but there were no significant differences in pathogenicity in wheat and rice. These results contribute to the knowledge of the effect of crop rotation on Fusarium mycotoxins and species affecting cereals in Sichuan Province, which may lead to improved strategies for control of Fusarium mycotoxins and fungal disease in China.

Climate controls over phenology and amplitude of net ecosystem productivity in a wheat-maize rotation system in the North China plain

Climate controls over phenology and amplitude of net ecosystem productivity in a wheat-maize rotation system in the North China plain

Responses of crop production and soil health to chemical nitrogen fertilization in a maize-wheat rotation system

Chemical nitrogen (N) fertilizer is generally applied at high rates to maximize crop yields and also many non-grain farmlands are being converted into grain production to ensure grain production safety in China now. To test the effects of chemical N on crop production and soil health, a 3-year trial with urea and controlled-release fertilizer was conducted in a maize (Zea mays L.)-wheat (Triticum aestivum L.) system shifted from vegetable farmland by evaluating the effects of N fertilization on crop yields, typical soil properties, and soil bacterial community using 16S rRNA gene sequencing. The maximum crop yield and aboveground N uptake efficiency was achieved at 150 kg N ha-1 for wheat and 200 kg N ha-1 for maize. After three cropping seasons, the soil N properties were notably altered. For each kg of N applied, soil pH decreased at a rate of 0.0004–0.0012 pH units. The soil total N (TN) and total carbon (TC) content reached a higher stability at certain cumulative N application rates. However, the C/N ratio linearly decreased as N rate increased. Consequently, N application significantly decreased soil bacterial diversity owing to the decrease of α-diversity indexes of Shannon and Pielou_e. At the phylum level, chemical N application significantly depleted members of Acidobacteria, Chloroflexi and Nitrospirae, but the growth of Actinobacteria, Gemmatimonadetes, Firmicutes and Patescibacteria were improved. Compared with urea, the controlled-release fertilizer did not significantly change crop yields, soil bacterial diversity, soil TN and TC content. Overall, our results indicated that chemical N promoted crop yields at optimum application rates, but excessive N application could result in a decline in soil health, specifically accelerated soil acidification, a decrease in soil bacterial diversity, and soil C and N imbalance.

Alleviating groundwater depletion while realizing food security for sustainable development

Groundwater depletion was one of humanity's greatest challenges for both food and environmental security. Here we tried to address these challenges through a meta-analysis in three major global groundwater-depleted agricultural regions and a case study with the long-term field experiment with factorable and systematic solutions. We showed groundwater depletion was particularly evident in the important regions for global food production, such as the High Plains of the United States, the Ganges Plains of India, and North China Plain, resulting from a 262.5 mm gap between crop water demand and rainfall. In order to solve this problem, the long-term field study in North China Plain indicated that the factor adjustment (minimum irrigation) within the traditional system and systematic change from traditional wheat-maize rotation to double-cropped maize could achieve both sustainable groundwater use and high calorie yield, accompanying by low integrated environmental impacts. Our results provided essential insights in similar areas for the United Nations Sustainable Development Goals for food and environmental security.

Maize straw mulching with no-tillage increases fertile spike and grain yield of dryland wheat by regulating root-soil interaction and nitrogen nutrition

Straw mulching increases soil water availability, but the influence of tillage practices with straw mulching on soil water, soil nitrogen, root distribution, and the physiological response of wheat plants is poorly understood. Field experiments (2013–2017) were conducted to determine the combined effects of straw mulching (0 and 8,000 kg ha−1) and tillage methods (no-tillage, rotary tillage, and plow tillage) on soil water, N, root distribution, plant N nutrition, tiller capability, and grain yield of dryland wheat. Straw mulching with no-tillage showed higher soil moisture, mineral N, and Olsen-P content than no-mulch with rotary tillage or plow tillage. These changes increased the total root length and surface area in the 0–20 cm soil layer but not in the 20–40 cm soil layer. Topsoil foraging strategies of root increased total N uptake, wheat return N from straw, and N balance while reducing N surplus, indicating that maize straw harvesting by mulching with no-tillage leads to a more efficient N recycling in the winter wheat–summer maize rotation system. Straw mulching with no-tillage showed greater aboveground plant dry mass and shoot N%, leading to increased plant N nutrition, tillering capability, and grain yield. Our results indicated that maize straw mulch with no-tillage increased fertile spike and grain yield by increasing soil water and N availability and maximizing root-soil interactions among the different combinations studied. Maize straw mulching with no-tillage could hence be recommended to dryland farming communities to transition from rotary tillage to a no-tillage conservation system and to increase soil and crop productivity in the maize-wheat rotation system.

Reclaimed Salt-Affected Soils Can Effectively Contribute to Carbon Sequestration and Food Grain Production: Evidence from Pakistan

Salt-affected soil reclamation provides opportunities for crop production and carbon sequestration. In arid regions such as Pakistan, limited studies have been reported involving soil reclamation and crop production under wheat–maize rotation, but no study has reported predictions on long-term carbon sequestration in reclaimed soils for the treatments used in this study. Thus, a field-scale fallow period and crop production experiment was conducted for wheat–maize rotation on salt-affected soils in Pakistan for 3 years to check the effectiveness of organic amendments for reclamation of the salt-affected soils, carbon sequestration and food grain production. Treatments used were the control (with no additional amendments to reduce salinity), gypsum alone and gypsum in combination with different organic amendments (poultry manure, green manure, and farmyard manure). The treatment with gypsum in combination with farmyard manure was most effective at increasing soil carbon (+169% over the three-year period of the trial). The maximum wheat yield was also recorded in year 3 with gypsum in combination with farmyard manure (51%), while the effect of green manure combined with gypsum also showed a significant increase in maize yield in year 3 (49%). Long-term simulations suggested that the treatments would all have a significant impact on carbon sequestration, with soil C increasing at a steady rate from 0.53% in the control to 0.86% with gypsum alone, 1.25% with added poultry manure, 1.69% with green manure and 2.29% with farmyard manure. It is concluded that food crops can be produced from freshly reclaimed salt-affected soils, and this can have added long-term benefits of carbon sequestration and climate change mitigation.

Effect of different straw retention techniques on soil microbial community structure in wheat-maize rotation system.

Rotational straw return technique is considered an effective measure for improving soil quality and maintaining soil microorganisms. However, there are few reports on the influence of wheat-maize crop rotation and straw-returning tillage on crop soil microbial communities in China. This study aimed to investigate how wheat or maize straw-incorporation practices affect bacterial and fungal communities under wheat-maize rotational farming practices. To clarify the effects of straw incorporation on microbial composition, microbial communities from soils subjected to different treatments were identified using high-throughput sequencing. Our results showed that, before corn planting, wheat and maize straw returning reduced bacterial density and increased their diversity but had no effect on fungal diversity. However, before wheat planting, returning wheat and corn stalks to the field increased the diversity of soil bacteria and fungi, whereas returning corn stalks to the field reduced the diversity of fungi and other microorganisms. Straw return significantly increased the relative abundance of Ascomycota in the first season and decreased it in the second season; however, in the second season, wheat straw return increased the relative abundance of Bradyrhizobium, which can promote the soil microbial nitrogen cycle and provide nitrogen to the soil. Wheat and maize straw return increased the relative abundance of Chaetomium, whereas, individually, they decreased the relative abundance. In addition, we detected two fungal pathogens (Fusarium and Trichoderma) under the two planting patterns and found that the relative abundance of pathogenic Fusarium increased with wheat straw return (FW and SW). Trichoderma increased after treatment with maize straw return before wheat planting (S group). These results suggest that wheat straw return (FW and SW) and maize straw return might have a negative impact on the pathogenic risk. Therefore, further studies are needed to determine how to manage straw returns in agricultural production.

Long-term application of organic compost is the primary contributor to microplastic pollution of soils in a wheat–maize rotation

Microplastics (MPs) are posing new threats to soil ecosystems. Organic fertilizers are considered as an emerging contributor to MPs accumulation in agricultural soils. However, few studies have focused on the MPs fate in soils under long-term organic fertilizer application. Based on an 11-year field test with wheat-maize cropping rotation, this study investigated the characteristics of MPs in pig manure and cow manure composts, and examined the impact of long-term compost application on soil MPs accumulation, surface morphology, and distribution. The MPs contents in pig manure and cow manure composts were 3547 and 4520 items kg−1, respectively. Microplastics abundances in soils under long-term use of these two composts were 144 to 287 and 140 to 316 items kg−1, respectively, which increased significantly with increasing compost application amount and was substantially higher than that in soils without compost. Accumulated soil MPs sourced from long-term compost application were 1.73 × 108 to 7.22 × 108 items ha−1, accounting for 43.0 %–75.9 % of the total, and the contribution value doubled as the compost application rate doubled. The proportion of MPs <1 mm in composts (31.0 %) was lower when compared with that in compost-amended soils (43.8 %), and size and abundance reduced with increasing soil depth. Microplastics shapes and polymer types in composts and compost-amended soils were similar and mostly included fragments of polyethylene and polypropylene and fibers of polyethylene terephthalate. Microplastics in compost-amended soils showed complicated weathered surface morphologies, and soil mineral colloids were attached. These results demonstrate that compost-derived MPs in soils can be gradually weathered and degraded into smaller particles under long-term compost application. These findings provide key insights into the pollution level of soil MPs with organic fertilizer application and serve as a scientific basis for developing MPs mitigation measures in agricultural soils.

Significant reduction of ammonia emissions while increasing crop yields using the 4R nutrient stewardship in an intensive cropping system

Ammonia (NH3) emissions should be mitigated to improve environmental quality. Croplands are one of the largest NH3 sources, they must be managed properly to reduce their emissions while achieving the target yields. Herein, we report the NH3 emissions, crop yield and changes in soil fertility in a long-term trial with various fertilization regimes, to explore whether NH3 emissions can be significantly reduced using the 4R nutrient stewardship (4Rs), and its interaction with the organic amendments (i.e., manure and straw) in a wheat–maize rotation. Implementing the 4Rs significantly reduced NH3 emissions to 6 kg N ha–1 yr–1 and the emission factor to 1.72%, without compromising grain yield (12.37 Mg ha–1 yr–1) and soil fertility (soil organic carbon of 7.58 g kg–1) compared to the conventional chemical N management. When using the 4R plus manure, NH3 emissions (7 kg N ha–1 yr–1) and the emission factor (1.74%) were as low as 4Rs, and grain yield and soil organic carbon increased to 14.79 Mg ha–1 yr–1 and 10.09 g kg–1, respectively. Partial manure substitution not only significantly reduced NH3 emissions but also increased crop yields and improved soil fertility, compared to conventional chemical N management. Straw return exerted a minor effect on NH3 emissions. These results highlight that 4R plus manure, which couples nitrogen and carbon management can help achieve both high yields and low environmental costs.

Effectiveness of Conventional and Minimized Tillage Practices on Soil Quality Properties and Maize Yield Attributes

The effects of tillage systems on soil properties and crop productivity have been the subject of many studies to ensure sustainable productivity. Aims: In the study, the effects of different tillage methods applied in the intermediate period of wheat-maize rotation on the soil quality properties and corn yield elements were investigated in the pre-planting period (PP) and plant growth period (PGP) of corn. Methods: Conventional tillage (CT), minimum tillage with subsoiling and chisel (MT1), minimum tillage with subsoiling (MT2), minimum tillage with chisel (MT3) and direct sowing (DS) methods were compared. As a result of the tillage practices, at 0-20 cm, the highest bulk density values were measured in the DS and CT methods, and 20-40 cm was determined in the CT method. The penetration resistance values of the soils measured at a depth of 0-80 cm were significantly affected by the applications made in both PP and PGP. The highest saturation value was measured in the MT3, the highest field capacity and plant available water contents were measured in the DS. The effects of the applications on the chemical properties of the soil and the nutrient content of the corn plant were limited. The effects on only grain protein ratio from yield components of corn plant were significant, the highest value was measured in CT. Considering the sustainable management of soils labour requirement and lower costs it was concluded that DS and MT methods are more applicable than CT methods in terms of yield.

Potassium management and residue recycling effects on wheat (Triticum aestivum) under maize (Zea mays) – wheat rotation

The crop residue application and the balanced fertilization with 3 major macronutrients mainly emphasizing on different potassium management practices significantly improve the yield attributing components of wheat crop. Likewise, the highest grain, straw and biological yield in wheat crop was observed with crop residue retention and the split application of 100% RDK (½ at basal + ½ top dress at 25 DAS). The maximum production efficiency and monetary efficiency was recorded under the crop residue retention. Among the potassium management practices the efficiencies were recorded maximum with the split application of 100% RDK (½ at basal + ½ top dress at 25 DAS). Hence, it can be concluded that for enhanced productivity and greater monetary efficiency, the crop residue retention and the split application of 100% RDK (½ at basal + ½ top dress at 25 DAS) could be a better management practice for better growth and development of wheat crop in a maize-wheat rotation. However, to have greater insights on the residue retention and potassium effects, the future research may focus on understanding water and nutrient release pattern in the soil profile, improvement in soil physical and mechanical properties, rhizospheric microbial dynamics and physiological effects on the wheat plants due to diverse residue management systems and potassium application protocols.

Plastic film-mulched ridges and straw-mulched furrows increase soil carbon sequestration and net ecosystem economic benefit in a wheat-maize rotation

The application of soil mulching has been widely used to increase crop production in arid, semi-arid, and sub-humid areas, with plastic film-mulched ridges and straw-mulched furrows (RFPS) proving to be more effective as compared with other soil mulching practices. However, few research studies have comprehensively assessed the impacts of RFPS on greenhouse gas (GHG) emissions, grain yield, net ecosystem carbon budget (NECB), and net ecosystem economic budget (NEEB) compared against the single practices of either plastic film mulching or straw mulching. A three-year field experiment was conducted on a wheat (Triticum aestivum L.)-maize (Zea mays L.) rotation field in the southern Loess Plateau, China. Four treatments were evaluated: (1) conventional flat planting without mulching (CK), (2) flat planting with plastic film mulching (PM), (3) flat planting with straw mulching (SM), and (4) RFPS. All mulching practices significantly increased wheat and maize yields as well as the seasonal cumulative carbon dioxide (CO2) emissions from soil respiration (Rs) and ecosystem respiration (Re) compared with CK. RFPS had the greatest annual grain yield and the greatest Rs for wheat seasons. The average annual NECB values for CK and PM were − 1.47 and − 1.05 Mg CO2-eq ha−1 yr−1, respectively, where the negative values indicated that the soil in CK and PM acted as a carbon (C) source. SM and RFPS acted as C sinks because of the straw C input, having average annual NECB values of 1.46 and 1.74 Mg CO2-eq ha−1 yr−1, respectively. PM, SM, and RFPS significantly increased the average annual NEEB by 31.4%, 70.5%, and 60.3%, respectively, compared with CK. Although RFPS had greater C input and grain yield income, it also had greater Rs, harvest removal C loss, and agricultural input costs, resulting in similar NECB and NEEB to what was observed with SM. Considering that the greatest grain yields were obtained with RFPS, this production practice should be a promising method for maintaining greater, more stable crop production, while increasing soil C sequestration and NEEB for the wheat-maize cropping system in dry semi-humid regions such as the southern Loess Plateau of China.

Key soil properties influencing infiltration capacity after long-term straw incorporation in a wheat (Triticum aestivum L.)–maize (Zea mays L.) rotation system

Straw incorporation is increasingly being adopted in wheat (Triticum aestivum L.)–maize (Zea mays L.) rotation systems to improve soil physiochemical properties. To identify the main soil properties influencing infiltration capacity under long-term straw incorporation in a wheat–maize rotation system, the study set four treatments: no straw incorporation and fertilizer application, wheat straw incorporation with 276 kg nitrogen/ha, wheat and maize straw incorporation with 276 kg N/ha, and wheat and maize straw incorporation. The initial, average, and final infiltration rates were calculated to represent soil infiltration capacity. Compared with other treatments, wheat straw incorporation with 276 kg nitrogen/ha treatment significantly decreased soil bulk density, soil aggregate (DMWD) mean weight diameter measured using the dry sieving method, and weight rate of soil aggregates with diameters greater than 0.25 mm measured using the wet sieving method, and significantly increased total soil porosity, soil capillary porosity, field capacity, and weight rate of soil aggregates with diameters less than 0.25 mm measured using the wet sieving method. In contrast, wheat and maize straw incorporation treatment significantly increased soil bulk density and noncapillary porosity, but decreased total soil porosity, capillary porosity, and field capacity. The results of partial least squares regression indicated that the soil moisture content and DMWD were the primary factors influencing initial infiltration rate with positive regression coefficient. Higher total soil porosity, capillary porosity, field capacity, and DMWD contributed to higher final infiltration rate, while higher soil bulk density and noncapillary porosity were correlated with a lower final infiltration rate. The key influencing factors of average infiltration rate were soil bulk density, soil moisture content, total soil porosity, capillary porosity, and DMWD. The wheat straw incorporation with 276 kg nitrogen/ha treatment had higher infiltration rates than no straw incorporation and fertilizer application treatment. However, with an increase in straw amount, the influence of straw on infiltration showed a law of diminishing marginal returns. Therefore, wheat and maize straw incorporation with 276 kg nitrogen/ha treatments had a lower infiltration rate than wheat straw incorporation with 276 kg nitrogen/ha treatment. In addition, wheat and maize straw incorporation treatment had the lowest average and final infiltration rates of all treatments, indicating that excessive straw incorporation without nitrogen fertilizer had adverse effects on infiltration rates. This study furthers understanding of the influence of long-term straw incorporation on soil hydrological processes and helps rationally use straw resources in wheat–maize rotation systems.

Diversified crop rotations reduce groundwater use and enhance system resilience

Agricultural intensification has increased crop productivity but simplified production and reduced cropping system diversity. In recent decades, the intensified wheat–maize rotation in the North China Plain has sharply decreased the groundwater table, with associated environmental and biodiversity issues. Understanding whether increasing cropping system diversity stabilizes productivity, improves resilience, and reduces adverse environmental impacts is critical. This study quantified the water requirements of nine staple crops from 1960 to 2020, established 15 alternative crop rotations, and evaluated the resilience of each rotation in the Cangzhou area, a typical groundwater deletion funnel area. The results showed that reducing cropping density (harvests per year) from 2 to 1.5 decreased the average annual water requirement and irrigation demand by 14 % and 33 %, respectively. Summer soybean alternated with maize and rotated with wheat did not reduce groundwater use but increased profitability and protein production. Spring mung bean–summer millet-based multi-rotations had higher precipitation coupling degrees (8 % in wet years, 17 % in normal years, and 56 % in dry years) and profitability (1.1–2.4 times) than the wheat–maize rotation. The spring potato–summer millet rotation in one year had the greatest profitability, the highest equivalent yield to wheat, and the highest water use efficiency (WUE), while spring maize rotated with winter wheat–summer soybean performed best for protein content, energy output, and WUEs. This study identified 11 alternative rotations with a higher comprehensive evaluation index than the conventional wheat–maize rotation based on entropy-TOPSIS considering 12 indicators. Spring mungbean is not suitable for inclusion in the crop rotation when solely cultivated in one year due to mismatched rainfall. Beyond wheat and maize, soybean, millet, and potato are promising crops for innovative multi-year multi-crop rotations to enhance crop diversification, maximize system outputs, and minimize groundwater and energy depletion. This study’s analysis could be extended to develop robust and diverse crop rotations with multiple co-benefits in other water-stressed agricultural regions.

Biofumigation for the Management of Fusarium graminearum in a Wheat-Maize Rotation.

Fusarium graminearum is the most important causal agent of head blight in wheat, and stalk and ear rot in maize. A field experiment was conducted to investigate the effect of incorporation of Brassicaceae cover crops on Fusarium graminearum in a wheat-maize rotation. Five species belonging to Brassicaceae (Brassica juncea, Eruca sativa, Raphanus sativus, B. carinata, B. oleracea var. caulorapa L.) were used in the field experiment to investigate their potential to suppress F. graminearum inoculum in soil, disease incidence in maize and to reduce subsequent mycotoxin contamination in maize. Brassica juncea was found to contain the highest glucosinolate concentration in shoots (31 µmol g-1). Severity of ear rot and stalk rot in maize was not significantly reduced in the amended plots. Incorporation of R. sativus 'Terranova' significantly decreased the amount of F. graminearum DNA by 58% compared with the cultivated fallow treatment, however the DNA concentration was not significantly different to fallow uncultivated. Fusarium graminearum DNA and deoxynivalenol in maize was 50% lower after incorporation of B. oleracea var. caulorapa L. compared to after fallow treatment but the difference was not significant. The brassica crops used in the present field experiment were not effective in suppressing F. graminearum, therefore further studies to optimise the current approach are recommended.

Effects of applying river sediment with irrigation water on salinity leaching during wheat-maize rotation in the Yellow River Delta

In the Yellow River Delta, soil salinization and river sediment are the two factors influence on economic growth. A large area of salinization reduces crop yields and dredged river sediment increases management costs. This study evaluated the effects of applying sediments under different levels of irrigation on salinity leaching for improving field productivity. A three-year field experiment (from June 2017 to June 2020) was conducted by considering three levels of sediment application:a control (no sediment added, S1), 30▒mm ha−1 (S2) and 60▒mm ha−1 (S3), and three levels of irrigation water: 290▒mm (90▒mm maize + 200▒mm wheat, W1), 385▒mm (120▒mm maize + 265▒mm wheat, W2) and 480▒mm (150▒mm maize + 330▒mm wheat, W3). The results exhibited that soil leaching rate was up to 66.3 % under 60▒mm ha−1 sediment application and 385▒mm irrigation after three wheat-maize rotation cultivation. This irrigation and sediment applied strategy achieved the effect of leaching salt, saving water and increasing grain yields. The mean yield of wheat and maize in sediment application and irrigation treatment was 18.3▒t ha−1 in three-year experiment which was significant bigger than the control. Thus, it is a technically feasible and friendly sustainable approach for salinization soil development in the Yellow River Delta.

Impacts of vermicompost application on crop yield, ammonia volatilization and greenhouse gases emission on upland in Southwest China

Ammonia (NH3) volatilization and greenhouse gas (GHG) emission are important environment pollution sources in upland agro-ecosystems. Vermicompost was used for amending purple soil and comparing NH3 and GHG emissions. A field experiment was conducted with a comparison of organic and inorganic fertilizers in a wheat–maize rotation system in the Sichuan Basin, China. The five treatments were conventional inorganic fertilizers, NPK as control; vermicompost prepared with cow dung (VCM); and pig manure (VPM); cow dung and pig manure vermicompost, respectively (VCMNPK, VPMNPK). Total nitrogen rates of all treatments were the same. Soil NH3 volatilization and GHG emissions were monitored with the static chamber method. The results showed that NH3 volatilization occurred in the first two weeks following nitrogen (N) fertilization. The cumulative fluxes of NH3 recorded in the NPK, VCM, VPM, VCMNPK, and VPMNPK treatments were 15.4, 5.7, 6.3, 10.32, and 10.29 kg N ha−1 yr−1, respectively, in the winter and 4.8, 5.5, 19.83, 12.8, and 11.9 kg N ha−1 yr−1 respectively, in the summer. The global warming potential (GWP) 773.6 and 803.9 g CO2-eq m−2 in VCM and VPM, respectively, during the wheat season 540.6 and 576.2 g CO2-eq m−2, respectively, during the maize season. The GWPs in NPK treatment were 1032.4 and 570.7 g CO2-eq m−2 during the wheat and maize seasons, respectively. The increasing effects of nutrient loops, particularly 18 % soil total nitrogen (TN) and 31 % soil organic carbon (SOC) in VCM, and crop productivity of vermicompost treatments during the wheat–maize rotation had been evaluated. This study recommends that VCM can be considered as a better organic amendment, promoting plant growth while decreasing the environmental costs of gas emissions.