Wheat-maize System Research Articles

Long-Term Fertilization and Lime-Induced Soil pH Changes Affect Nitrogen Use Efficiency and Grain Yields in Acidic Soil under Wheat-Maize Rotation

Liming (L) is a common practice to mitigate soil acidification and enhance soil quality and crop productivity. However, in acidic soil, it is not clear how long-term application of lime and nitrogen (N)-based fertilizer affects soil chemical properties, the wheat and maize grain yields (GY), and N-use efficiency (NUE). Thus, to investigate the effects of N-based fertilizations without L (−L) and with L (+L) on wheat and maize GY and NUE through their effects on soil chemical properties, we analyzed a 28-year field experiment in acidic soil under a wheat-maize system in South China. The analysis was carried out between 1991 and 2010 (before L) and between 2011 and 2018 (after L). We categorized the treatments into (1) no fertilizer (C); nitrogen (N); N and phosphorus (NP); N and potassium (NK); N, P and K (NPK); and NPKCR, NPK and crops residue (CR) applications (NPKCR), before L; and (2) C; N−L; N+L; NP−L; NP+L; NK−L; NK+L; NPK−L; NPK+L; NPKCR−L and NPKCR+L, after L. The effects of long-term fertilization resulted in lower soil pH by 15%, soil available K (AK) by 19%, POlsen by 6%, NO3−-N by 15%, soil organic matter (SOM) by 16%, total N by 16%, and C:N ratio by 13% in −L soil than in +L soil. However, the accumulation of NH4+-N was higher by 40% in −L soil than in +L soil. Wheat and maize GY, N recovery efficiency (REN), and N partial factor productivity (PEPN) were more adversely affected by 8-year fertilizations in −L compared with fertilizations before L and in +L primarily because of the significantly decreased soil pH. Conversely, improvements in wheat and maize yields, REN, and PFPN by 8-year fertilizations in +L were related to increasing soil pH, exchangeable base cations such as Ca2+, Mg2+, and the alleviated toxicity of Al3+. Overall, improvement of GY and NUE from the acidified soil in South China requires the long-term integrated use of fertilizer (NPK), retention of CR, and the +L (i.e., NPKCR+L).

Effect of nutrient management on yield, economics, water and energy use efficiency of maize (Zea mays) under conservation agriculture based maize-wheat (Triticum aestivum) system

A field experiment was conducted under long-term conservation agriculture (CA)-based maize (Zea mays L.)-wheat (Tricum aestivum L.)-mungbean (MWMb) system at ICAR- IARI, New Delhi (2017-18 and 2018-19) in split-plot design to compute the yields, economic, water and energy use-efficiency. There were 3-tillage treatment in main-plots and 4-nutrient management options in sub-plots with 3-replications. Results of present study showed that the grain yield of maize was 21.1% higher in CA-based permanent bed (PB) than conventional till (CT) plots. Net returns and net benefit cost ratio in PB plots was higher by 46.1 and 55.4% compared to CT, respectively (2-year mean basis). Two year mean basis water use-efficiency (WUE), net energy output and energy use-efficiency (EUE) were higher by 17.0, 26.3 and 12.5% in PB plots than CT. No significant effect of tillage was observed on N, P and K content (grains and stover). However, the total N, P and K uptake in maize grains and stover was higher by 23.6, 24.5 and 22.4% under PB than CT plots, respectively. Among nutrient management options; 2-year mean basis maize grain yield was 31.6 and 29.7% higher in Green Seeker (GS) guided-N and site specific nutrient management (SSNM) plots than farmers fertilizer practice (FFP), respectively. Net returns and BC ratio were also higher by 51.4-53.4% and 41.35-42.6% in GS guided-N and SSNM than FFP plots, respectively. WUE, net energy output and EUE were also significantly higher in GS guided-N treatment than FFP. Total N, P and K uptake were also significantly higher in GS guided-N and SSNM plots compared to FFP.

Short-Term Assessment of Nitrous Oxide and Methane Emissions on a Crop Yield Basis in Response to Different Organic Amendment Types in Sichuan Basin

Agriculture’s goal to meet the needs of the increasing world population while reducing the environmental impacts of nitrogen (N) fertilizer use without compromising output has proven to be a challenge. Manure and composts have displayed the potential to increase soil fertility. However, their potential effects on nitrous oxide (N2O) and methane (CH4) emissions have not been properly understood. Using field-scaled lysimeter experiments, we conducted a one-year study to investigate N2O and CH4 emissions, their combined global warming potential (GWP: N2O + CH4) and yield-scaled GWP in a wheat-maize system. One control and six different organic fertilizer treatments receiving different types but equal amounts of N fertilization were used: synthetic N fertilizer (NPK), 30% pig manure + 70% synthetic N fertilizer (PM30), 50% pig manure + 50% synthetic N fertilizer (PM50), 70% pig manure + 30% synthetic N fertilizer (PM70), 100% pig manure (PM100), 50% cow manure-crop residue compost + 50% synthetic N fertilizer (CMRC), and 50% pig manure-crop residue compost + 50% synthetic N fertilizer (PMRC). Seasonal cumulative N2O emissions ranged from 0.39 kg N ha−1 for the PMRC treatment to 0.93 kg N ha−1 for the NPK treatment. Similar CH4 uptakes were recorded across all treatments, with values ranging from −0.68 kg C ha−1 for the PM50 treatment to −0.52 kg C ha−1 for the PM30 treatment. Compared to the NPK treatment, all the organic-amended treatments significantly decreased N2O emission by 32–58% and GWP by 30–61%. However, among the manure-amended treatments, only treatments that consisted of inorganic N with lower or equal proportions of organic manure N treatments were found to reduce N2O emissions while maintaining crop yields at high levels. Moreover, of all the organic-amended treatments, PMRC had the lowest yield-scaled GWP, owing to its ability to significantly reduce N2O emissions while maintaining high crop yields, highlighting it as the most suitable organic fertilization treatment in Sichuan basin wheat-maize systems.

Site-specific nutrient management under conservation agriculture-based spring wheat in Trans-Gangetic Plains of India

The experiment was conducted during 2018-19 and 2019-20 at ICAR-IARI research farm, to see the effect of crop establishment and nutrient management options on growth and yield of wheat under maize-wheat system. The experiment was laid out in split plot design with 03 replications, comprising conventional tillage without residue (CT-R), conventional tillage with 3 t/ha residue (CT+R), permanent raised bed without residue (PRB-R) and permanent raised bed with 3 t/ha residue (PRB+R) in main plot and nutrient management, viz. soil test-based(STB), Nutrient Expert® based (NE) and NE+ GreenSeekerTM based recommendations (NE+GS) in sub-plot. A significantly (P≤0.05) higher crop growth, viz. plant height, dry matter accumulation and leaf area index under PRB+R compared to other crop establishment technique. Differentyield parameters (yield, grain straw ratio and harvest index) and yield attributes of wheat grown under PRB+R were significantly higher (P≤0.05) over other crop establishment technique. A significantly (P≤0.05) higher crop growth, yield attributes, grain yield (5.01 and 5.05 t/ha), grain: straw ratio (0.65 and 0.65) and harvest index (39.31 and 39.36) of wheat were recorded with NE+GS based fertilization during 2018-19 and 2019- 20, respectively. Pearson correlation matrix analyzed for different growth and yield parameters showed a significant positive correlation (r) among themselves. Study infer that growing of wheat on the permanent raised bed along with 03 t/ha residue retention on surface and precision nutrient prescription using NE and GreenSeekerTM optical sensor showed promise for sustainable high productivity in intensively cultivated Trans-Gangetic Plains.

Advantages of an Orychophragmus violaceus-maize rotation in reducing greenhouse gas emissions and reactive nitrogen losses and increasing net ecosystem economic benefits on the North China Plain

Introducing cover crops into crop rotation systems is widely practiced to enhance the sustainability of agricultural production, but comprehensive evaluations of farmlands in cover crop-maize rotations on the North China Plain (NCP) from environmental, economic and net ecosystem economic benefits (NEEB) perspectives have rarely been performed. Therefore, a field experiment was conducted to compare economic benefits (EB), greenhouse gas (GHG) emissions, reactive nitrogen (Nr) losses, soil nutrient cycling values (SNV) and NEEB in three farming systems. The farming systems included a conventional wheat-maize (WM) rotation system, a government-promoted monoculture maize (MM) system and an innovative Orychophragmus violaceus (O. violaceus)-maize (OvM) rotation system. The OvM rotation system achieved more EBs from the maize season but lower annual profits than the WM system, with 68.29% lower GHG emissions and 39.33% lower Nr losses. In addition, the highest SNV was achieved in the OvM rotation system, which was 700.18% and 116.97% higher than those in the WM and MM systems, respectively. Furthermore, the NEEB of the OvM rotation system was 61.92% and 29.31% higher than those of the WM and MM systems, respectively. In conclusion, the OvM rotation is recommended as a sustainable and cleaner maize production farming system for the NCP and other regions with similar ecological conditions because it led to lower annual GHG emissions and Nr losses, as well as higher SNV and NEEB than the other farming systems.

Effects of long-term phosphorus application on crop yield, phosphorus absorption, and soil phosphorus accumulation in maize-wheat rotation system.

In this study, we examined the effects of four phosphorus treatments on crop yields, and analyzed crop phosphorus uptake and phosphorus utilization efficiency, as well as changes in soil phosphorus deficit in maize-wheat rotation system, based on a 7-year field experiment in Baoding City, Hebei Province. The results showed that long-term phosphorus application significantly increased the yield and phosphorus uptake of maize and wheat. The yield and phosphorus uptake of maize and wheat showed a parabolic trend that first increased and then decreased with the increases of phosphorus application. The utilization efficiency of phosphorus fertilizer in the corn season was higher than that in the wheat season under various phosphorus application treatments. The cumulative utilization efficiency of phosphorus fertilizer in the wheat season showed a downward trend. The decline rate showed that optimized phosphorus application > 70% optimized phosphorus application >130% optimized phosphorus application. The cumulative utilization efficiency of phosphorus fertili-zer in the corn season showed an upward trend. For the rising rate, the optimized phosphorus application > 70% optimized phosphorus application > 130% optimized phosphorus application. Both the apparent phosphorus surplus and the accumulated phosphorus surplus of the soil without phosphorus application were under phosphorus deficiency. Under the treatment of phosphorus application, soil phosphorus showed a status of phosphorus surplus. The higher the phosphorus application rate, the longer the accumulation period, the higher the soil phosphorus surplus. Under the straw returning condition, phosphorus application rate for wheat of 105-150 kg·hm-2 and the phosphorus application rate for maize of 63-90 kg·hm-2 in Hebei fluvo-aquic soil could ensure the high crop yield, keep the phosphorus utilization efficiency at a high level, and reduce soil phosphorus accumulation and environmental risks.

Land gradient and configuration effects on yield, irrigation amount and irrigation water productivity in rice-wheat and maize-wheat cropping systems in Eastern India

Laser land levelling is expanding rapidly in the rice-wheat (RW) and maize-wheat (MW) systems of the Indo-Gangetic Plains of India and Pakistan. Current practice is to level to zero (0%) gradient, whereas a small gradient (e.g. 0.1%) is typically used in developed countries. Therefore, experiments were conducted in farmers’ plots (~15 m x 40 m) in the Eastern Gangetic Plains to evaluate laser levelling with a 0.1% gradient in comparison with 0% and farmer levelling practice (FL). The study was conducted over two years in RW and MW systems. In the MW system, raised beds in plots lasered with 0% and 0.1% gradients were also evaluated. Laser levelling with 0% gradient significantly reduced irrigation amount and/or increased irrigation water productivity (WPi) in all crops/systems grown on the flat compared to FL except for wheat in the MW system. While there was a consistent trend for higher yield with a 0% gradient compared with FL, the differences were not significant in any crop/system. For the RW system, the results suggest no to marginal benefits in irrigation amount and WPi from levelling with a 0.1% gradient in comparison with 0% gradient. In that system, by far the bigger gains were from changing from FL to laser levelling with 0% gradient. This resulted in substantial reductions in irrigation amount, which greatly increased WPi in both crops (by ~40%), while yield was not affected. Rice grown with FL was not profitable, but lasering with 0% gradient significantly increased gross margin for rice, wheat and the total RW system. As for the RW system, levelling to 0% with a flat configuration significantly increased WPi of both crops in the MW system compared to FL, but by a lesser proportion. Raised beds significantly increased yield of maize by 8% (0.5 t ha−1), reduced irrigation amount by 20% (40 mm) and increased WPi by 34% (1.0 kg m−3) in comparison with the laser levelled flat plots. Gross margin of the MW system on beds was 17–20% higher than FL, and gross margin with beds on a 0.1% gradient was significantly higher than either gradient on the flat. The results suggest that the gains from levelling with a 0.1% gradient compared to 0% are marginal; however, this may change if the goal of consolidation of small farmer plots into larger fields becomes a reality provided there is a proportionate increase in irrigation flow rates, and ability to drain.

Soil Carbon Fractions at Different Soil Depths as Influenced by Land use Practices under Cropping Systems in a Vertisol

The experimental field study was conducted at Borlaug Institute for South Asia (BISA) Research Farm, Lakhanwada, Jabalpur, Madhya Pradesh, India to evaluate the soil carbon fractions (very labile, labile, less labile and non-labile or recalcitrant carbon) in different land use practices with soil depths under cropping systems in Vertisols after harvest of Kharif and Rabi season crops of year 2015-16 and 2016-17. The experiment was conducted under Split plot design considering land use practices as main plot treatments [L1: Uncultivated, L2: rice-wheat system with conventional agriculture (CT), L3: rice-wheat system with conservation agriculture (CA), L4: soybean-wheat system with CT, L5: soybean-wheat system with CA, L6: maize-wheat system with CT and L7: maize-wheat system with CA] and depth (0-5 cm, 5-15 cm and 15-30 cm) as sub-plot treatments replicated thrice. Very labile carbon fraction was obtained highest in L3 (rice-wheat system with CA) and lowest under L6 (maize -wheat system with CT) treatment after harvest of Kharif and Rabi season crops during 2015-16 and 2016-17and it was significantly higher at 0-5 cm soil depth than those in 5-15 cm and 15-30 cm soil depths. Similar trends were also obtained in case of labile, less labile and non-labile fraction of carbon i.e. the applied land use practices had significant effect on all the carbon fractions under study and found to be maximum under L3 (R-W system with CA) and minimum in L6: (M-W system with CT) treatment after harvest of both the season crops during both years of experiment. Whereas, the interaction effect of land use practices and soil depths on the carbon fractions was found statistically non-significant during both the seasons and years.

Achieving Sustainability in Food Systems: Addressing Changing Climate through Real Time Nitrogen and Weed Management in a Conservation Agriculture-Based Maize–Wheat System

The proven significance of conservation agriculture (CA) in enhancing agronomic productivity and resource use efficiency across diverse agro-ecologies is often challenged by weed interference and nitrogen (N) immobilization. The collective effect of real-time N and weed management has been scarcely studied. To evaluate the appropriateness of sensor-based N management in conjunction with a broad-spectrum weed control strategy for the maize–wheat system, an experiment was conducted at ICAR—Indian Agricultural Research Institute—in New Delhi, India, during 2015–2016 and 2016–2017. Weed management in maize through Sesbania brown manure followed by post-emergence application of 2,4-D (BM + 2,4-D) in maize and tank-mix clodinafop-propargyl (60 g ha−1) and carfentrazone (20 g ha−1) (Clodi+carfentra) in wheat resulted in minimum weed infestation in both crops. It also resulted in highest maize (5.92 and 6.08 t ha−1) and wheat grain yields (4.91 and 5.4 t ha−1) during 2015–2016 and 2016–2017, respectively. Half of the N requirement, when applied as basal and the rest as guided by Optical crop sensor, resulted in saving 56 and 59 kg N ha−1 in the maize–wheat system, respectively, over 100% N application as farmers’ fertilizer practice during the two consecutive years. Interactive effect of N and weed management on economic yield of maize and wheat was also significant and maximum yield was obtained with 50% N application as basal + rest as per Optical crop sensor and weed management through BM+2,4-D in maize and Clodi+carfentra in wheat crop. The study concludes that real-time N management, complemented with appropriate weed management, improved growth, enhanced agronomic productivity and endorsed N saving under a CA-based maize–wheat system in Trans Indo-Gangetic Plains.

Energy budgeting and carbon footprints of three tillage systems in maize-wheat sequence of north-western Indo-Gangetic Plains

Intensive tillage often contributes to yield gains but there is a tradeoff with energy consumption and carbon footprint (CF) challenging agricultural and environmental sustainability. Studies in the past examined the effect of tillage practices on one or two of the metrics viz., crop productivity or energy auditing or CF and a comprehensive evaluation of the three in a single study to identify cleaner and climate-smart production practice is generally lacking. This study quantified the effect of conventional (CT), deep (DT) and no-tillage (NT) with and without straw mulch on energy budgeting, crop productivity, CF and greenhouse gas intensity (GHGI) in maize-wheat sequence in a split plot design field experiment. No-tillage in maize curtailed energy input by 38.4% and 20.1% compared to DT and CT, respectively. Per tonne of maize grain production, NT with mulch (NTM) saved 1044 MJ of energy (41%) and increased grain yield by 35.3% compared with CT without mulch (CTM0). Although grain yield and net energy gain was higher under DT with mulch (DTM) than NTM, yet latter resulted in significantly higher energy productivity and energy use efficiency. Minimum C equivalent emissions and maximum gain in soil organic C in NTM lowered the CF resulting in highest C efficient and sustainable management. Minimal GHGI without yield penalty was achieved by adopting NT with mulching. Energy and C budgeting revealed that NT coupled with mulching is the most energy and C efficient practice followed by DTM; CT without residue retention is the least efficient management practice for intensively cultivated maize-wheat system in north-western Indo-Gangetic Plains.

Evaluating soil physical quality indicators of a Vertisol as affected by different tillage practices under wheat-maize system in the North China Plain

Soil physical quality (SPQ) is an important parameter for crop growth. Tillage management is widely recognized to affect SPQ remarkably, but such an effect is complicated in Vertisols by shrinking and swelling soil structure. The objectives of this study were to (i) investigate how tillage practices affected SPQ as indicated by the S index, least limiting water range (LLWR) and water stress percentage (WSP); and (ii) determine the relationship between these SPQ indicators and crop yield. A 4-year field experiment, which was conducted in a Vertisol under wheat-maize rotation system in the North China Plain, consisted of four tillage treatments: no tillage (NT), rotary tillage (RT), subsoiling (SS), and deep ploughing (DP). Soil water retention curve (SWRC), soil shrinkage curve (SSC), penetration resistance (PR), and bulk density (BD) of the 0−10 and 10−20 cm layer were measured during wheat and maize seasons, and soil water content was continuously monitored in situ. The S index, LLWR and WSP were determined. Our results showed that SSCs were parallel to each other among four tillage treatments, indicating that tillage did not impact shrinkage capacity (P > 0.05). Relative to NT and RT treatments, the SS and DP treatments improved soil physical quality (higher S index and larger LLWR), particularly in the 10−20 cm layer. The S index presented a poor relation with wheat (P > 0.05) and maize yields (P > 0.05), while LLWR had a significant correlation with wheat yield (P < 0.05) but not with maize yield (P > 0.05). A new proposed SPQ indicator, WSP, is defined as the percentage of the period when the soil water content is above the field water capacity (waterlogging stress percentage, WLP) or below the wilting point (drought stress percentage, DSP) to the entire crop season period. The WLP presented a significantly negative relation with maize yield (P < 0.01) but not with wheat yield (P > 0.05), whereas the DSP had no relation with wheat and maize yield (P > 0.05). Moreover, the WSP was observed to be independent of the volume change in the Vertisol. Our results demonstrate that LLWR and WLP can be regarded as suitable indicators for evaluating SPQ in wheat and maize seasons, respectively, but the latter is more conveniently applied in a Vertisol.

Crop residue and potassium management strategies to improve water use and soil microbial activities under zero till maize (Zea mays)-wheat (Triticum aestivum) cropping system

A field experiment was conducted with maize-wheat system during 2014-15 and 2015-16 at ICAR-IARI, New Delhi to study the soil microbial activities, crop growth, water use and its related parameters of maize and wheat as influenced by crop residue (CR) and potassium (K) management practices under zero till maize (Zea mays L.)-wheat (Triticum aestivum L.) system. The experiment was laid out in split-plot design with four CR levels (0, 2, 4 and 6 t/ ha) and five K levels (0, 50%, 100%, 150% RDK [recommended dose of K] and 50% RDK + potassium solubilizing bacteria, KSB). The results revealed that significantly higher biomass production, water use efficiency (WUE), irrigation water productivity (IWP) and total water productivity (TWP) of maize and wheat were found with 4.0-6.0 t/ha CR as compared to no CR and 2.0 t/ha CR.This was in consonance with improvement in soil microbial activities. Among K management, 50% RDK+KSB, 100% RDK and 150% RDK were found significantly superior over no K and 50% RDK for soil microbial activities, biomass production, WUE, IWP and TWP of maize and wheat. Thus, a combination of 4.0-6.0 t/ha CR retention and 50% RDK along with seed inoculation of KSB microbial strain could be pre-eminent options to improve crop growth, water use efficiency and soil microbial activities in zero till maize-wheat system.

Can ridge-furrow with film and straw mulching improve wheat-maize system productivity and maintain soil fertility on the Loess Plateau of China?

Ridge-furrow mulching patterns are beneficial to improve crop yields and rainwater use efficiency, but it is not clear whether they can improve productivity and simultaneously maintain soil fertility on the Loess Plateau of China. A three-year (2013–2016) field trial was conducted during the rotation of wheat (Triticum aestivum L.) – maize (Zea mays L.) to investigate the effects of ridge-furrow mulching patterns on soil moisture, soil fertility, grain yield, and water use efficiency (WUE). Four ridge-furrow planting patterns included: (1) white plastic film mulch over the ridge (RW), (2) straw mulch over the furrow (RS), (3) white plastic film mulch over the ridge and straw mulch over the furrow (RWS), and (4) black plastic film mulch over the ridge and straw mulch over the furrow (RBS). Flat planting without mulch was CK. The results showed that RW, RS, RWS, and RBS significantly improved soil water storage and aboveground biomass throughout each winter wheat and summer maize growing season compared with CK. Finally, winter wheat grain yield and WUE in the four mulching treatments markedly increased by 13.0–32.9% and 22.5–41.5% in a wet and cool season, 15.5–35.2% and 19.3–41.9% in a season with normal rainfall and temperatures, and 27.2–58.9% and 15.3–33.4% in a dry and warm season, respectively. Maize grain yield and WUE increased by 12.8–35.0% and 19.5–46.2% in a season with normal rainfall and temperature, 15.0–38.5% and 18.0–39.9% in a dry and cool season, and 17.4–50.5% and 13.0–42.5% in a dry and warm season, respectively. Among the four mulching treatments, RWS and RBS significantly improved the yield and WUE of wheat and maize relative to RW and RS over the three years. After three years, soil total nitrogen content in RWS and RBS was significantly greater than in RS. Besides, soil microbial biomass carbon and nitrogen, and soil dissolved organic carbon and nitrogen contents in RWS and RBS were all markedly higher than in RW and RS. Our results indicated that RWS and RBS were a promising agricultural practice that improved crop production and simultaneously maintained soil fertility in a rain-fed semi-arid region of China.

Designing profitable, resource use efficient and environmentally sound cereal based systems for the Western Indo-Gangetic plains

In the western Indo-Gangetic plains, issues of deterioration in soil, water, and environment quality coupled with low profitability jeopardize the sustainability of the dominant rice–wheat (RW) system. To address these issues, crop diversification and conservation agriculture (CA)-based management hold considerable promise but the adoption of both approaches has been low, and additional evidence generation from a multi-criteria productivity and sustainability perspective is likely required to help drive the change. Compared to prevailing farmers’ practice (FP), results suggest that CA-based rice management increased profitability by 13% and energy use efficiency (EUE) by 21% while reducing irrigation by 19% and global warming potential (GWP) by 28%. By substituting CA-based maize for rice, similar mean profitability gains were realized (16%) but transformative improvements in irrigation (− 84%), EUE (+ 231%), and GWP (− 95%) were observed compared to FP. Inclusion of mungbean in the rotation (i.e. maize-wheat-mungbean) with CA-based management increased the system productivity, profitability, and EUE by 11, 25 and 103%, respectively while decreasing irrigation water use by 64% and GWP by 106% compared to FP. Despite considerable benefits from the CA-based maize-wheat system, adoption of maize is not widespread due to uneven market demand and assured price guarantees for rice.

Long-term use of balanced fertilization decreases nitrogen losses in a maize-wheat system on Inceptisol of north India

ABSTRACT Soil nitrogen (N) distribution and crop utilization are closely related to fertilizer management and crop productivity. The present study, based on 47-year fertilizer focused on a cropping system (maize-wheat) based budgeting of N which is necessary to identify its sources and losses to improve fertilizer use efficiency, crop productivity, and environmental sustainability. Long-term application of fertilizer has a positive effect on soil TN (total nitrogen) and TOC (total organic carbon), which increased by 36–107% and 24–103%, respectively compared to control. Integrated application of fertilizer and farmyard manure registered 266% higher grain yield of maize-wheat over the control but the addition of 50% higher NPK than recommended NPK showed no yield advantage and reduced recovery of fertilizer N by 23% (maize) and 22% (wheat) relative to NPK. Accounting all the N inputs and outputs, NPK application (least N loss) has 49–85 kg ha−1 lower N loss compared to NP and N application, respectively. It has concluded that the long-term use of recommended and balanced fertilizer alone or in combination with FYM has the potential to improve N and C status of soil and its recovery by decreasing its loss, which increases the productivity of the maize-wheat system.

Photosynthetic characteristics and productivity in a wheat–maize system under varying zinc rates

AbstractThe photosynthetic rate (Pn) and leaf area index (LAI) play an important role in dry matter production. To understand the role of Zn fertilizer in increasing the yield of winter wheat (Triticum aestivum L.) and summer maize (Zea mays L.) by regulating Pn and LAI, a field experiment with six Zn rates (0, 2.3, 5.7, 11.4, 22.7, and 34.1 kg Zn ha−1) was conducted from 2013 to 2015 on a calcareous soil. Zinc application increased wheat and maize yield by 4–19% and 4–13%, respectively, across the 2 yr. The aboveground biomass, Pn, and LAI of both wheat and maize also significantly increased with increasing Zn rates. Structural equation modeling showed that the yield increase of wheat mainly depended on the Pn and LAI, whereas that of maize mainly depended on the Pn. The relationships of the Pn and LAI with shoot Zn concentrations followed a linear‐plateau trend for wheat and linear for maize. The optimal shoot Zn concentrations to obtain the maximal Pn and LAI of wheat were determined to be 46–49 mg kg−1. Zinc application at 11.4 kg Zn ha−1 was an optimal rate to guarantee yield attainment and Zn biofortification. The results of this study are useful for farmers to optimize their Zn fertilizer management in agricultural systems to obtain high yields.

Deep tillage and irrigation impact on soil water balance and water productivity of maize-wheat cropping system in north-west India

ABSTRACT The subsurface compact soil layer hampers the root growth of crops and affects the crop water productivity. It is imperative to study the deep tillage impact on soil water balance and water productivity of maize-wheat cropping system. A two-year (2016–18) field experiment was conducted with two irrigation regimes in main plots based on irrigation water to pan evaporation ratio 1.2 (I1.2) and 0.8 (I0.8) in maize and 1.0 (I1.0) and 0.5 (I0.5) in wheat; and three tillage treatments in subplots (i) conventional-tilled maize followed by conventional-tilled wheat (MCT-WCT), (ii) deep tillage before the sowing of maize during first season followed by conventional-tilled wheat (MDT1-WCT) (iii) deep tillage before the sowing of maize during both the seasons followed by conventional-tilled wheat (MDT2-WCT). The irrigation water input was lower by 75 mm and 225 mm in I0.8/I0.5 than I1.2/I1.0 during 2016–17 and 2017–18, respectively. The evapotranspiration of maize and wheat was significantly higher with frequent irrigation regime. The water productivity was significantly higher under I0.8/I0.5 than under I1.2/I1.0 in 2017–18. The deep tillage helped in increasing the water productivity of maize-wheat system, the effect being similar with respect to frequency of deep tillage.

Residue and Potassium Management Strategies to Improve Crop Productivity, Potassium Mobilization, and Assimilation under Zero-Till Maize–Wheat Cropping System

Understanding of the potassium (K) nutrient cycle and its microbial transformation of unavailable forms of soil K to plant-available K is crucial in any agroecosystem for strategic nutrient management through inorganic fertilizer, crop residue (CR), and microbial applications. Therefore, the present investigation was undertaken to study the effect of crop residue and K management practices on crop productivity, K mobilization from native soil K-pool, and crop assimilation of K under a zero-till maize–wheat cropping system. The experiment consisted of four residue levels (0, 2, 4, and 6 Mg ha−1) and five K levels (0, 50%, 100%, 150% RDK [recommended dose of K] and 50% RDK + potassium solubilizing bacteria, KSB). Results showed that CR retention at 6.0 Mg ha−1 significantly improved grain yield (of maize by 10.17%; wheat by 9.87%), dry matter accumulation, K uptake and redistribution in native soil K pools (water soluble K (WSK), exchangeable K (EK) and non-exchangeable K (NEK)) at 30 and 60 days after sowing and at harvest as compared to no CR. Among the K management, 50% RDK+KSB reported significantly higher grain yield (of maize by 26.22%; wheat by 24.70%), dry matter accumulation, K uptake, and native K pools (WSK, EK, and NEK) at different growth stages compared to no K. Total K did not differ significantly due to residue and K management. The highest actual change of K reported with 6.0 Mg ha−1 CR (51 kg ha−1) and 50% RDK+KSB (59 kg ha−1) over control. Significant (p ≤ 0.01) positive correlation was found among grain yield, dry matter accumulation, K uptake, the actual change in K and different native K pools. It can be concluded that retention of 6 Mg ha−1 CR and supply of 50% K through inorganic fertilizer along with seed inoculation of KSB biofertilizers, improved crop growth, productivity by enhancing K assimilation as a consequence of the release of non-exchangeable K and through the application of CR and K treatments under a zero tillage maize–wheat system.

Does the replacement of chemical fertilizer nitrogen by manure benefit water use efficiency of winter wheat – summer maize systems?

Manure has been used as a source of nutrients in grain crop production for millennia worldwide. However, whether and how manure applications benefit water use efficiency (WUE) still remains incomplete, especially in the North China Plain under water deficient conditions. A three-year split-plot field experiment was established with (W1) and without (W0) irrigation at the wheat jointing stage as main plots. Fertilization treatments were included as sub-plots with no fertilizer (F0), 100 % chemical fertilizer N (Fc), 100 % manure N (Fm), and 50 % chemical fertilizer N + 50 % manure N (Fc + m). W1 rarely affected WUE of winter wheat in the normal season, but increased that by 67 % in the dry season, compared to W0. W1 had a rare effect on evapotranspiration (ET) and WUE of summer maize. Overall, W1 decreased annual WUE of wheat-maize system by 9% in the normal years, while it increased that by 8% in the dry years. Manure application (Fm and Fc + m) increased WUE of winter wheat by 5–9 % compared to chemical fertilization (Fc), due to the lower ET after anthesis. However, manure application decreased WUE of summer maize by 6–10 % than chemical fertilization, which caused by the higher ET before anthesis. Therefore, fertilization strategies had a minor effect on annual WUE of wheat-maize system. In conclusion, the replacement of mineral N with manure under deficient irrigation provides a better fertilization strategy to maintain annual WUE of wheat-maize system, which has the potential to relieve the regional water scarcity for sustainable agriculture production in the North China Plain.

System productivity and economics influenced by residue and potassium management in maize (Zea mays)-wheat (Triticum aestivum) rotation

A field experiment was conducted during kharif and rabi 2014-2016 at ICAR-IARI, New Delhi to study the system productivity, economics and energetics of maize (Zea mays L.) and wheat (Triticum aestivum L.) as influenced by crop residue (CR) and potassium (K) management under zero till maize-wheat system. The experiment was laid out in split plot design with four CR levels (0, 2, 4 and 6 t/ha) and five K levels (0, 50%, 100%, 150% RDK [recommended dose of K] and 50% RDK+Potassium solubilizing bacteria, KSB). Results revealed that significantly higher system productivity, output energy, specific energy and highest energy intensiveness, actual change in available K were found with 4.0-6.0 t/ha CR. Maximum B: C ratio in maize-wheat system was observed with No CR followed by 2.0-4.0 t/ha CR. Highest net energy returns, energy use-efficiency, energy productivity and lowest input energy (351- 395%) in both crops were registered with No CR fb 2.0-4.0 t/ha CR. Among K management, 50% RDK+KSB was significantly superior over rest levels. The maximum system net returns, B:C ratio, output energy, net energy returns, energy use-efficiency and energy productivity were found in 50% RDK+KSB and consumed only 0.34-0.35% higher input energy over no K in maize and wheat. Change in available K was more in 150% RDK fb 50% RDK+KSB and 100% RDK. Thus, a combination of 2.0-4.0 t/ha CR retention and 50% RDK along with seed inoculation with KSB improved system productivity, net returns and energetic parameters in zero tillage maize-wheat system, and brought positive change in available K and hence can be recommended for adaptation by the farmers.