Wheat-maize Cropping System Research Articles

Optimal Fertilizer Application Reduced Nitrogen Leaching and Maintained High Yield in Wheat-Maize Cropping System in North China.

Agricultural nitrogen (N) non-point source pollution in the North China Plain is a major factor that affects water quality and human health. The characteristics of N leaching under different N application conditions should be further quantified accurately in winter wheat (Triticum aestivum L.) and summer maize (Zea mays L.) rotation farmland in North China, and a basis for reducing the risk and evaluation of N leaching in this area. A three-year field experiment was conducted using an in situ leakage pond method at a typical farmland in Henan in 2017–2020. Crop yield, soil nitrate N residues, and N utilization were also studied during the study period. Five N fertilizer rates were established with 0 (CK), 285 (LN), 465 (MN), 510 (MNO), and 645 (HN) kg N ha−1 for one rotation cycle. MNO was applied with chemical and organic fertilizers. The concentration of nitrate N in the soil leaching solution of CK, LN, MN, MNO, and HN was 0.81-, 1.49-, 3.65-, 5.55-, and 7.57-fold that of the World Health Organization’s standard for underground drinking water. The exponential relationship between the N application rate and leaching was obtained when the annual N input exceeded 300 kg ha−1, and the N leaching rate increased greatly. The leaching rate of nitrate N in the total N was 50.6–82.4% under different treatments of N application. The combination of chemical and organic fertilizers treatment (MNO) reduced the amount of N that was leached in dry years. The nitrate leaching amount of summer maize accounts for 83.0%, 49.4%, and 72.0% of the total nitrate leaching amount of the whole rotation cycles in 2017–2020. LN and MN were recommended as the optimized N application here (285–465 kg N ha−1) with the two-season rotation grain yield of 17.2 ton ha−1 (16.5–17.9 ton ha−1) and nitrate N leaching of 21.6 kg ha−1 (12.6–30.5 kg ha−1).

Assessing the impact of climate change in the wheat–maize cropping system across the Huang–Huai–Hai Plain under future climate scenarios

Abstract General circulation models suggest that changes in climatic parameters will have an effect on food production globally. Therefore, this study assessed the impact of climate change on wheat–maize rotation areas in the Huang–Huai–Hai Plain (3H Plain). The projections generated suggest an increase in precipitation during the wheat growth period (WGP) by 1.33–4.16% (2.6–8.3 mm) and 3.13–8.16% (6.2–18.0 mm) under RCP4.5 and RCP8.5, respectively, relative to the base period (1981–2016). Across the 3H Plain, the mean temperature during the WGP is projected to increase between 1.17–1.21 and 1.17–1.28 °C under RCP4.5 and RCP8.5, respectively. The projections during the maize growth period (MGP) indicate an increase in the temperature between 1.29–1.92 and 1.84–2.08 °C under RCP4.5 and RCP8.5, respectively. During the MGP, precipitation is also projected to increase by 7.41–9.73% (33.6–45.1 mm) and 6.63–14.78% (29.8–72.7 mm) under RCP4.5 and RCP8.5 scenarios, respectively. For each 1% change in climatic factors, the comprehensive effect on yield was projected to be 0.65 and 0.58% for wheat and −1.08 and −1.11% for maize, under RCP4.5 and RCP8.5, respectively, when other factors were kept constant. The change in water resources will be insignificant during the WGP and more pronounced during the MGP. The study provides an overview of changes in meteorological parameters and scientific evidence for climate change adaptation in the wheat–maize cropping system.

Integration of peach (Prunus persica L) remnants in combination with beneficial microbes and phosphorus differ phosphorus use efficiency, agronomic efficiency and partial factor productivity in soybean Vs maize crops

Phosphorus (P) is an essential nutrient which can increase crop production, plant biomass, economic yield and profitability. The objectives of this research were to investigate the impact of peach sources (PS), beneficial-microbes and phosphorus levels on P use-efficiency (PUE), agronomic-efficiency (AE) and partial-factor productivity (PFP) in soybean and maize crops under soybean-wheat and maize-wheat cropping-systems. Peach remnants (leaves, twigs, stones and barks non-decomposed, compost and biochar) along with three P-levels (50, 75, 100 kg-ha−1) and two beneficial-microbes (PSB and Trichoderma) were used in the experiment. The results revealed that PS had significant effect on soybean and maize PUE, AE and PFP. PUE in soybean and maize were noted differ (25.6 and 28.4%) with integration of peach biochar as compared to compost and residues application. In case of P application highest PUE in soybean was recorded with 75 kg-P-ha−1(22.2%), while in maize PUE was noted with 50 kg P ha−1(33.5%). Trichoderma was promising and observed deviation in PUE for soybean (21.7%) and maize (27.8%) as compared to PSB. PAE and PFPp in soybean and maize altered with PS and highest values for AE and PFP were noted with biochar. Among the P levels, the highest PAE was recorded with 75 kg P-ha−1 in both crops, whereas PFPp in soybean was maximum with 75 kg P-ha,−1 and interestingly in maize it was noted with 50 kg-ha−1. Conclusively, PAE, PFPp and PUE were higher with biochar + Trichoderma + 75 kg P-ha−1 and can improve soybean and maize yield and productivity on sustainable basis.

Effect of Various Weed Management Practices on Weed Dynamics and Crop Yields under Maize-Wheat Cropping System of Western Hills

Weeds pose a great challenge to cereal farmers and need to be managed before reaching the critical stage. An experiment was conducted to evaluate effect of various weed management practices on the weed dynamics and crop yields under the maize-wheat cropping system in 2019-2020 at research field of Directorate of Agricultural Research, Lumle, Kaski. The experiments consisted of six pre- emergence and post-emergence chemical management practices (Tembotrione post-emergence (PoE), Pendimethalin as pre-emergence (PE), Atrazine as (PoE), Atrazine as PE fb Tembotrione as PoE, Pendimethalin as PE fb 2,4-D Ethyl Ester (EE), Pendimethalin as PE fb Tembotrione as PoE for maize crop; Pendimethalin as PE, Pendimethalin as PE fb Manual weeding, Pendimethalin as PE fb Metribuzin, Pendimethalin as PE fb 2,4-D sodium salt as PoE, 2,4 D sodium salt as PoE, Metribuzin as PoE for wheat crop) compared with manual weeding and weedy check both maize and wheat. These treatments were studied in a randomized complete block design (RCBD) with three replications. Ageratum conyzoides and Chenopodium album were found to be the major weeds for the maize and wheat crop respectively. Atrazine as pre-emergence fb Tembotrione as post–emergence produced the highest yield (3.575 Mt ha-1) for maize season whereas 4.8 Mt ha-1 was obtained in Metribuzin treated plot as post emergence herbicide in wheat growing season. The yield increments by Tembotrione as post emergence was 71.51% and Metribuzin was 63.09% over weedy check. The findings could be useful for researchers and maize-wheat growing farmers of high rainfall ecologies.

Zinc dynamics and yield sustainability in relation to Zn application under maize-wheat cropping on Typic Hapludalfs

Globally, widespread micronutrient deficiencies have become a serious challenge for sustaining crop production systems and food security. Of all micronutrients, zinc (Zn) is the most deficient one. Hence, efficient Zn management is essential to achieve potential crop yields. A six-year field experiment was conducted on Typic Hapludalfs with maize-wheat cropping system to study the direct and residual Zn management effect on maize and succeeding wheat crop, respectively. The effect on soil available Zn was also evaluated. Three Zn application frequencies, viz. once (single year), alternate (every alternate year), and continuous (every year) at four Zn application rates, viz. 2.5, 5.0, 7.5, and 10.0 kg ha −1 along with one control (no Zn) were investigated from 2013 to 2019. The Zn application significantly improved the crop yields, system sustainability, DTPA-Zn, and different Zn pools without causing any environmental risk. In general, the continuous application of Zn at 5.0 kg ha −1 produced the best yield and system productivity. The economically optimal system productivity was obtained with 5.93 and 7.46 kg Zn ha −1 for alternate and continuous frequency Zn application, respectively. The optimal DTPA-Zn to attain the highest system productivity of 7.64 t ha −1 was 1.55 mg kg −1 . The crop yields were mainly influenced by the alternate and continuous application of Zn at lower rates (2.5, 5.0, and 7.5 kg ha −1 ), whereas Zn fractions and DTPA-Zn were significantly influenced by Zn application at higher rate (10 kg ha −1 ) irrespective of Zn application frequencies. Similar results were obtained with PCA analysis. The results of this study suggested the rationality of Zn application in attaining economically viable and environmentally sound maize-wheat system productivity.

Soil organic carbon and nitrogen storage under a wheat (Triticum aestivum L.)-maize (Zea mays L.) cropping system in northern China was modified by nitrogen application rates.

Field cultivation practices have changing the carbon and nitrogen cycles in farmland ecosystem, soil organic carbon (SOC) and total nitrogen (TN) were the important parameters in maintaining soil quality and increasing agricultural productivity, however, N application’s effects on the SOC and TN storage capacity under intensive wheat-maize cropping system remain unclear. Therefore, we investigated the characteristics and relationships of SOC and TN for wheat-maize cropping system under nitrogen treatments. In doing so, continuous applications of four nitrogen application rates were examined: 0, 180, 240 and 300 kg ha−1 (N0, N180, N240 and N300, respectively). Wheat yields under N180 and N240 were significantly higher than that under N300, while the maize yields under N180, N240 and N300 were significantly higher than that under N0 by 79.79, 85.23 and 86.85%, respectively; the TN content and storage were significantly higher under N240 than that under other N levels in 40–60 cm soil layer after wheat growing season; the SOC content and storage under N180 and N240 were significant higher than that under N300 in 20–40 cm after maize growing season. The correlations between SOC and TN contents (or storage) were stronger after wheat planting than maize planting. These findings provide a basis for further studies on the effect of long-term N application on SOC and TN storage, crop quality and nitrogen use efficiency under wheat-maize cropping systems.

Economic Profitability and Carbon Stock Potential of Cereals and Pulses Under Harar and Aonla Based Agroforestry Systems in The Low Hill Zone of Himachal Pradesh

Practicing wheat-maize cropping system by the farmers of Himachal Pradesh is less economical viable as compared to pulses. Besides this, pulses have high potential of soil improvement through nitrogen fixation. Hence, the experiment was premeditated to evaluate the carbon stock potential and economic profitability of cereals and pulses under Harar and Aonla based agroforestry systems in the low hill zone of Himachal Pradesh. The experiment was conducted with nine treatment combinations with four replications in RBD. Highest biomass (77.80 t ha-1) and carbon stock (38.05 t ha-1) were recorded under maize+Harar. In term of economics, maximum gross returns (80,471.49 ` ha-1) were obtained for maize+Aonla yet, the maximum net returns (42,684.40 ` ha-1) and BC ratio (2.14) were found for mash+Aonla.

Soil Nutrient Balance and Soil Fertility Status under the Influence of Fertilization in Maize-Wheat Cropping System in Nepal

Soil nutrient balance is affected by nutrient management in crops. A poor nutrient management technique results in an imbalance in the soil nutrient status which could have a long-term negative impact on crop production. The current study was carried out to assess the effect of different rates of nitrogen (N), phosphorus (P), and potassium (K) on soil nutrient balance in a maize-wheat cropping system in Cambisols of Khumaltar, Lalitpur, Nepal during 2019/20 and 2020/21. The experiment included three-factor randomized complete block design with three doses of each N, P, and K which was replicated three times. There was a remarkable change in soil pH, soil organic carbon (SOC), and total N, P, and K contents of soil over a period of time with the application of different doses of NPK. Soil pH changed from 5.98 to 5.53, SOC increased from 11.7 to 16.8 g·kg−1, total N decreased from 1264 to 1177 mg·kg−1, available P2O5 declined from 214 to 63.6 mg·kg−1, and available K2O decreased from 71.7 to 24.8 mg·kg−1 with varying rates of NPK after four cropping seasons. Furthermore, partial, apparent, and net N, P, K balance were predominantly negative in all the fertilizer treatments, but the magnitude was lower under higher nutrient rates and positive partial N balance was noticed in higher N levels. The depletion of native P and K pools even at higher application rates was attributed to higher crop removal over time as compared to inputs. Therefore, continuous application of balanced fertilizers is crucial in maintaining the fertility of soil and productivity of crops.

Assessing Soil Physical and Chemical Properties Under Long Term Fertilization After Forty-Eight Years in North-Western Himalayas

ABSTRACT The present investigation was carried out in an on-going long-term fertilizer experiment, initiated during 1972 at experimental farm of Department of Soil Science, Choudhary Sarwan Kumar Himachal Pradesh Krishi Vishwavidyalaya Palampur, to study the long-term effect of fertilizers and amendments on soil physical and chemical properties in an acid Alfisol under maize–wheat cropping system. The experiment consisted of 11 treatments with 3 replications with randomized block design. The soil of the experimental site was silt loam and classified taxonomically as “Typic Hapludalf” (Subgroup). Long-term use of integrated nutrient management practices significantly improved the available Nitrogen, Phosphorus and Potassium as compared to control. Effect of long-term application of inorganic fertilizers and amendments on soil chemical properties was studied. Soil organic carbon content was increased in 100% Nitrogen, Phosphorus and Potassium + Farm Yard Manures applied plots. Application of inorganic fertilizers along with Farm Yard Manures increased the Mean weight diameter (MWD) and Geometric mean weight diameter (GMD) over control. The available Nitrogen, Phosphorus and Potassium and Diethylenetriamine pentaacetate (DTPA) extractable micronutrients cation were optimum in 100% Nitrogen, Phosphorus and Potassium + Farm Yard Manures applied treatments.

Effects of tillage and straw management on grain yield and SOC storage in a wheat-maize cropping system

Climate change significantly impacts the prevailing climatic conditions and crop productivity. Although soil organic carbon (SOC) sequestration can mitigate global climate change, the SOC sequestration capacity and crop production under conservation tillage are unclear. This study assessed the dynamics and relationship between SOC storage and grain yield under conservation tillage over eight years. Four tillage and straw management treatments, including (i) no-tillage with straw retention (NTS, conservation tillage), (ii) conventional tillage with straw retention (CTS), (iii) no-tillage without straw retention (NT), and (iv) conventional tillage without straw retention (CT), were conducted. The results showed that the SOC content and storage in the 0–10 cm soil layer were significantly higher in NTS than in the other treatments. In contrast, SOC content and storage in the 10–30 cm layer were lower in NTS than in CTS (P < 0.05). Overall, the average SOC storage in the 0–30 cm was significantly higher in the straw returning treatment than without straw returning (P < 0.05). Moreover, SOC storage was not significantly different between NTS (35.7 Mg ha−1) and CTS (35.9 Mg ha−1). The wheat yield was lowest under NTS. Furthermore, the yield coefficient of variation under NTS was significantly lower than under CTS (P < 0.05). Maize yield was not significantly different between NTS and CTS. SOC storage in the 0–10 cm soil layer had a quadratic relationship with annual yield. These results indicate that NTS can positively sequester carbon, especially for the surface layer. However, to mitigate climate change and food insecurity, further advancements in NTS technology are required to improve crop yields and carbon sequestration capacity.

Does straw return increase crop yield in the wheat-maize cropping system in China? A meta-analysis

Straw return into agricultural soil is one of the most important management practices in China. However, the direction and magnitude of crop yield to straw return are inconsistent from individual studies in wheat-maize cropping systems of Chinese upland soils. Hence, we conducted a meta-analysis of 1071 comparisons from 177 peer-reviewed publications to evaluate the effect of straw return on the yield in the wheat-maize cropping system varied with climate conditions, management practices, and soil properties. Overall, crop yield response to straw return in the mono-cropping system (11.8%) is significantly greater than that in the double-cropping system (5.5%). The positive effect is obvious in regions with subtropical climates (> 15 °C annual temperature and > 800 mm annual precipitation). Without fertilizer application, straw return has no improvement on crop yield in the mono-cropping system, or even decreases crop yield by 2.42% in the double-cropping system, while it will yield more under N fertilizer application of 150–200 kg ha−1 yr−1 for mono (16.4%) and > 300 kg ha−1 yr−1 for double (6.99%) cropping system. For both cropping systems, yield increase peaked at around 10–15 years. The positive effect of straw return on crop yield is more obvious under the conditions with irrigation, and deep tillage. For straw return method, straw incorporation presents a greater effect than straw mulching does. The increase in crop yield after straw return is closely related to the improvement of soil organic carbon, soil structure and nutrients. Therefore, our results indicate that straw incorporation under the conditions with deep tillage, irrigation and fertilization, has great potential to increase crop yield in the wheat-maize cropping system.

Influence of straw mulch and no-tillage on soil respiration, its components and economic benefit in a Chinese wheat–maize cropping system

Optimizing economic benefit while reducing soil CO2 emissions in cropping systems has become the focus of agricultural study. We assessed the influence of short-term straw mulch and no-tillage on soil respiration (Rs), heterotrophic respiration (Rh), and autotrophic respiration (Ra), as well as economic benefit, in a traditional Chinese winterwheat and summermaize rotation system. Combinations of four treatments were tested: NS (no straw), SM (straw mulch), CT (conventional tillage) and NT (no-tillage). For wheat, SM significantly increased Rs in 2019 but significantly decreased Rs in 2020 relative to NS. NT significantly decreased Rs by 5.8% compared to CT from 2019 to 2020. For maize, during all three annual cycles, SM increased Rs relative to NS. NT increased Rs in 2018 with respect to CT but decreased it in 2019 and 2020. From the perspective of annual Rs both wheat and maize, SM increased Rs by 34.8%, 19.8%, and 18.8% in 2018, 2019, and 2020, respectively. NT increased Rs by 4.9%, −1.6%, and −0.7% in 2018, 2019, and 2020, respectively. The lowest annual Rs occurred for SM+NT in 2020. Relative to NS and CT, SM and NT promoted Rh but inhibited Ra for wheat during 2019 and 2020. For maize, SM increased Rh and suppressed Ra while NT had no significant effect on Rh and suppressed Ra. Therefore, SM increased Rs by promoting Rh, while NT decreased Rs by inhibiting Ra. In all treatments, Rh averaged 1.82–3.36 times higher than Ra. Soil temperature had a greater influence on temporal variations in soil respiration than soil moisture. Averaged from 2018 to 2020, the annual economic benefit was increased by 11.7% and 15.3% in SM and NT than NS and CT, respectively. Our results suggest that straw mulch and no-tillage should be promoted as an environment-friendly agroecosystem management practice for wheat and maize, as these practices can achieve a balance between improving economic benefit and reducing soil CO2 emissions, contributing to the mitigation of climate change and the early achievement of carbon neutrality goals.

Studies on tillage and green manuring for enhancing productivity of wheat (Triticum aestivum)

A field experiment was conducted in 2016–17 and 2017–18 during kharif and rabi season at agricultural research farm of BHU, Varanasi, to study the effect of different tillage practices and green manuring on productivity and profitability of maize-wheat cropping system. The experiment was laid out in split plot design comprising 20 treatments. The four different tillage practices, viz. T1 (Conventional tillage maize-Conventional tillage wheat), T2 (Minimum tillage maize-Minimum tillage wheat), T3 (Minimum tillage maize-Zero tillage wheat) and T4 (Zero tillage maize-Zero tillage wheat) were assigned to main plot and five summer green manuring treatments, viz. M1 (Summer fallowing), M2 (Dhaincha), M3 (Sunnhemp), M4 (Clusterbean) and M5 (Cowpea) were kept in sub plots. The treatment, T4 and T1 were at par with each other and registered higher yield attributing characters, grain (4814.61, 4931.94 and 4754.03, 4840.69 kg/ha during 2016–17 and 2017–18, respectively) and straw yield, quality and B:C ratio. In case of summer green manuring, M2 (Dhaincha) recorded higher yield attributing characters, grain and straw yield and quality (4846.27, 4957.54 kg/ha during 2016–17 and 2017–18, respectively) over other treatments but it was at par with M3 (Sunnhemp). It is recommended that ZT wheat and summer green manure Dhaincha residue mulching should be followed to achieve higher yield and profitability.

Various quantification methods for estimating ammonia volatilization from wheat-maize cropping system

Ammonia volatilization (AV) dominates the pathway of nitrogen (N) fertilizer losses in crops throughout the world. However, different methods are highly responsible for the different measurements of AV. The existing techniques were separated into static chamber methods (SCM), dynamic chamber methods (DCM), calibrated Dräger-tube method (DTM) and micrometeorological methods (MMM), which were analyzed by a meta-study of 595 observations from 33 published studies. An exponential relationship (P < 0.01) was found between AV and the N fertilizer applied to wheat and maize using all the methods. The amount of AV using SCM was the lowest. The AV monitored by DCM was 24.5%–55.0% (wheat) and 46.9%–65.0% (maize) lower than that for the DTM. Additionally, the AV measured by DTM did not differ significantly in the wheat season but was 58.9% lower (P < 0.05) in the maize season than that in the MMM. To reveal the influencing factors responsible that were for DCM and DTM, a field experiment was conducted during the period of Oct. 2016 to Oct. 2017. The study indicated that the AV was 15.8%–28.3% (wheat, P < 0.05) and 36.7%–44.2% (maize, P < 0.05) lower when monitored by the DCM than when estimated by DTM. The concentration of soil NH4+−N, air temperature, and wind speed positively correlated with the NH3 fluxes. In addition, there was a significant linear correlation (P < 0.01) between the AV measured by DCM and DTM when the wind speed was <1.5 m s−1. This study highlighted the fact that wind speed was the main factor that caused the large difference between DCM and DTM. Herein, DTM or MMM was first recommended, and DCM was accepted when wind speed was <1.5 m s−1 for quantitative estimates of AV. However, only a straight comparison between DCM and DTM under the same field experiment was done, the other comparisons only being based on similar fertilization and environmental conditions. Consequently, the differences between methods have to be treated carefully.

Improving long‐term crop productivity and soil quality through integrated straw‐return and tillage strategies

AbstractLong‐termagricultural sustainability receives increasing concerns owing to the inappropriate removals of crop straw with frequent tillage, causing soil degradation and reduced productivity. A 7‐yr field experiment was conducted to exploit the optimal integrated straw‐return and tillage strategy for maintaining soil quality and sustaining crop productivity in an intensive wheat (Triticum aestivum L.)–maize (Zea mays L.) cropping system in the Guanzhong Plain. Three strategies were tested for wheat: straw harvest (Wh), straw return with chopped straw distribution on soil surface (Wr) and with stubble 30–40 cm height (Ws); three strategies were for maize: straw harvest with rotary tillage (Mh), straw return with rotary tillage (Mr) and with subsoiling (Ms). Thus, nine integrated strategies were conducted per rotation period: WhMh, WhMr, WhMs, WrMh, WrMr, WrMs, WsMh, WsMr, and WsMs. The results indicated that the eight integrated strategies (except WhMh) promoted both wheat and maize grain yields, and showed the largest increase for the system productivity (+42.3%) and sustainable yield index (+43.0%) under WsMs relative to the WhMh. In addition, significant increases were observed in various soil quality indicators under integrated strategies, especially under WsMs. The system productivity responses were predominately determined by mean weight diameter, soil organic carbon, available nitrogen, and available phosphorus. Therefore, the integrated strategies of wheat straw return with stubble 30–40 cm height and maize straw return with subsoiling can be advised for maintaining soil quality and improving crop productivity in the wheat–maize cropping system in the long term.

Dynamics of organic carbon and nitrogen in deep soil profile and crop yields under long-term fertilization in wheat-maize cropping system

Soil organic carbon (SOC) and nitrogen (N) are two of the most important indicators for agricultural productivity. The primary objective of this study was to investigate the changes in SOC and N in the deep soil profile (up to 100 cm) and their relationships with crop productivity under the influence of long-term (since 1990) fertilization in the wheat-maize cropping system. Treatments included CK (control), NP (inorganic N and phosphorus (P) fertilizers), NPK (inorganic N, P and potassium fertilizers), NPKM (NPK plus manure), and M (manure). Crop yield and the properties of topsoil were measured yearly from 2001 to 2009. C and N contents were measured at five different depths in 2001 and 2009. The results showed that wheat and maize yields decreased between 2001 and 2009 under the inorganic fertilizer (NP and NPK) treatments. The average yield between 2001 and 2009 under the NP, NPK, NPKM, and M treatments (compared with the CK treatment) increased by 38, 115, 383, and 381%, respectively, for wheat and 348, 891, 2 738, and 1 845%, respectively, for maize. Different long-term fertilization treatments significantly changed coarse free particulate (cfPOC), fine free particulate (ffPOC), intramicroaggregate particulate (iPOC), and mineral-associated (mSOC) organic carbon fractions. In the experimental years of 2001 and 2009, soil fractions occurred in the following order for all treatments: mSOC>cfPOC>iPOC>ffPOC. All fractions were higher under the manure application treatments than under the inorganic fertilization treatments. Compared to the inorganic fertilization treatments, manure input enhanced the stocks of SOC and total N in the surface layer (0–20 cm) but decreased SOC and N in the deep soil layer (80–100 cm). This reveals the efficiency of manure in increasing yield productivity and decreasing risk of vertical loss of nutrients, especially N, compared to inorganic fertilization treatments. The findings provide opportunities for understanding deep soil C and N dynamics, which could help mitigate climate change impact on agricultural production and maintain soil health.

Build-up and utilization of phosphorus with continues fertilization in maize-wheat cropping sequence

Long-term phosphorus (P) fertilization in the maize-wheat cropping system in northwest India has led to a considerable build-up of Olsen-P concentrations in many fields that exceed the crop removal. Optimal P management in high Olsen-P soils is desirable to achieve sustainable crop production and reduce the fertilizer P inputs and risk of P transfer to water bodies. This study aimed at finding the impact of fertilizer P applications on crop yield, P uptake, P use efficiency, and P balance (P input minus P output) from a 10 years study on maize-wheat sequence having contrastingly different Olsen-P levels. The results revealed no response to both maize and wheat to P application rates beyond 13 kg ha −1 in ‘very high’ P (VHP) (>50.0 kg ha −1 ) soils and 26 kg ha −1 in ‘high’ P (HP) (22.5–50.0 kg ha −1 ) and ‘medium’ P (MP) (12.5–22.5 kg ha −1 ) soils. P fertilization, significantly enhanced average maize P uptake by 8% and 26% and wheat P uptake by 5% and 18% in VHP soils relative to HP and MP soils. The improved agronomic and recovery P efficiencies were obtained in VHP soils by reducing fertilizer P to 50% of the recommended fertilizer P (26 kg P ha −1 ). Without P application, the average Olsen-P declined at the rate of 3.43 kg P ha −1 year −1 in VHP soils leading to the highest negative P surplus in these soils. P fertilization rates of 26 kg P ha −1 or above caused soil P build-up in loamy sand soils irrespective of Olsen-P status, thereby increase soil P surplus ranging from 13.4 to 67.0 kg P ha −1 . Therefore, for attaining optimum yields and P use efficiency under intensively cultivated maize-wheat cropping sequence, long-term P balance, P availability in different Olsen-P soils should be undertaken while formulating P recommendations. • Olsen-P status and fertilizer P application influenced maize and wheat yields. • P balance is a reliable indicator of soil Olsen P dynamics in the long term. • Improved P use efficiencies can be achieved with 13 kg P ha −1 in high Olsen-P soils. • Phosphorus fertilization at 26 kg P ha −1 and above causes build-up of Olsen-P.

Greenhouse gas emissions from the wheat-maize cropping system under different tillage and crop residue management practices in the North China Plain

With increasing attention being placed on mitigating global warming and achieving agricultural sustainable intensification, conservation agriculture practices have gradually been implemented in the North China Plain (NCP). However, there are still knowledge gaps on the effects of conservation practices on greenhouse gas (GHG) emissions in this area. In this study, a four-year field experiment was conducted from 2014 to 2018 to assess the effects of tillage and crop residue management practices on the emissions of nitrous oxide (N2O) and methane (CH4). Subsequently, crop yields, area-scaled and yield-scaled total non-carbon dioxide (CO2) GHG emissions were assessed. Our research found that no-till (NT) decreased N2O emissions by 22.6% compared with conventional tillage (CT) in winter wheat (Triticum aestivum L.) seasons, but there was no difference between tillage practices in summer maize (Zea mays L.) seasons. Crop residue retention practice (+R) increased N2O emissions by 28.1% and 26.7% compared with residue removal practice (−R) in winter wheat and summer maize seasons, respectively. The NT soils took up more CH4 compared with the CT soils in summer maize seasons. Area-scaled total non-CO2 GHG emissions showed trends similar to those of N2O emission. Since crop residue retention improved the maize yield compared with the residue removal treatments, yield-scaled total non-CO2 GHGs emission did not differ between residue management practices in summer maize seasons. Our four-year field measurements indicated that no-till practice could be more useful as an option to mitigate non-CO2 GHG emissions in the wheat – maize cropping system.

Influence of zinc fertilization levels and frequencies on crop productivity, zinc uptake and buildup of soil zinc in maize–wheat system

The zinc (Zn) requirement under intensive cropping system is higher due to continuous mining and the zinc fertilizers applied to the soil being adsorbed on soil colloids. Hence, detailed information of Zn is essential to understand the bioavailability processes. The present study was undertaken on an ongoing experiment initiated in 2012 at research farm of Department of Soil Science, Ludhiana with Zn levels i.e., 2.5, 5.0, 7.5 and 10.0 kg Zn ha−1 and three frequencies (once in six-year, alternate year, and every year) along with a control treatment. The maize and wheat yield were highest with the application of 10 kg Zn ha−1 every year which was at par with 7.5 kg Zn ha−1 every year and alternate year. The Zn uptake in maize and wheat was highest with 10 kg Zn ha−1 every year, which was statistically at par with 7.5 kg Zn ha−1 every year and 10 kg Zn ha−1 alternate years. The values of different fractions of zinc were higher with the application of 10 kg Zn ha−1 every year which was at par with 7.5 kg Zn ha−1 of every year and 10 kg Zn ha−1of alternate year. The different fractions of Zn i.e., residual zinc, crystalline FeO bound zinc, amorphous FeO bound zinc, organically bound zinc, manganese oxide bound zinc, carbonate bound zinc, specifically adsorbed zinc and water soluble + exchangeable zinc contribute 56.7, 16.0, 7.5, 5.1, 5.0, 4.8, 2.3, 2.2% to total Zn in soil. In overall it is concluded that the application of 10.0 kg Zn ha−1 in alternate year was found better for obtaining high crop yield and Zn uptake and for maintaining optimum available Zn in maize–wheat cropping system.

Quantifying in situ N2 fluxes from an intensively managed calcareous soil using the 15N gas-flux method

Denitrification-induced nitrogen (N) losses from croplands may be greatly increased by intensive fertilization. However, the accurate quantification of these losses is still challenging due to insufficient available in situ measurements of soil dinitrogen (N2) emissions. We carried out two one-week experiments in a maize–wheat cropping system with calcareous soil using the 15N gas-flux (15NGF) method to measure in situ N2 fluxes following urea application. Applications of 15N-labeled urea (99 atom%, 130–150 kg N ha−1) were followed by irrigation on the 1st, 3rd, and 5th days after fertilization (DAF 1, 3, and 5, respectively). The detection limits of the soil N2 fluxes were 163–1 565, 81–485, and 54–281 μg N m−2 h−1 for the two-, four-, and six-hour static chamber enclosures, respectively. The N2 fluxes measured in 120 cases varied between 159 and 2 943 (811 on average) μg N m−2 h−1, which were higher than the detection limits, with the exception of only two cases. The N2 fluxes at DAF 3 were significantly higher (by nearly 80% (P<0.01)) than those at DAF 1 and 5 in the maize experiment, while there were no significant differences among the irrigation times in the wheat experiment. The N2 fluxes and the ratios of nitrous oxide (N2O) to the N2O plus N2 fluxes following urea application to maize were approximately 65% and 11 times larger, respectively (P<0.01), than those following urea application to wheat. Such differences could be mainly attributed to the higher soil water contents, temperatures, and availability of soil N substrates in the maize experiment than in the wheat experiment. This study suggests that the 15NGF method is sensitive enough to measure in situ N2 fluxes from intensively fertilized croplands with calcareous soils.