Conventional tillage and crop establishment methods for the rice–wheat (RW) system are input intensive (water, labour and energy). About 24.5 million tonnes of rice residues are burnt every year on farms in north-western India before sowing of wheat, causing air pollution and soil health degradation. Therefore, alternative tillage, crop establishment and residue management practices are needed for long-term sustainability of the RW system. A 4-year field study evaluated four tillage and crop establishment methods in rice (in main plots) and three tillage and rice residue management methods in wheat (in subplots) for their effects on yield, soil fertility, and profitability of the RW system. Average rice yields were similar under conventional puddled transplanted rice (PTR) and conventional till dry seeder rice (CTDSR). Both of these treatments produced significantly greater yields (10–16%) compared with zero till DSR (ZTDSR) and ZT machine transplanted rice in non-puddled soil, respectively, regardless of tillage and straw management methods in the previous wheat crop. Wheat yields in ZT wheat (ZTW) with 100% surface retention of rice residue (+R) were significantly greater than conventional till without residue retention after 2 years of experimentation, and accompanied by significant increases in macro-nutrient (potassium) availability in soil. The ZTW−R (no residue) treatment produced 15% lower wheat yield than ZTW+R. System yield was highest in CTDSR-ZTW+R, which was 5% higher than the conventional practice PTR-CTW−R, resulting in Rs 17 000 ha−1 greater net returns.

ABSTRACT We studied the effects of tillage, crop residues, and green manure on soil carbon pools and hydrolytic enzyme activity in a sandy loam after five cycles of the rice-wheat system (RWS). Four main plot treatments in rice were combinations of wheat straw and Sesbania green manure (GM) management: (1) puddled transplanted rice (PTR) with no wheat straw, (2) PTR with 25% wheat stubbles (12–15 cm long) retained, (3) PTR with no wheat straw plus GM, and (4) PTR with 25% wheat stubbles plus GM. Three subplots treatments in subsequent wheat were (1) conventional tillage with rice straw removed, (2) zero tillage (ZT) with rice straw removed, and (3) ZT with 100% rice straw retained as a surface mulch. The results showed that PTR with wheat stubbles retained plus GM and ZT wheat with rice straw retained (ZTWRS100) significantly (p< 0.05) increased all the carbon pools and hydrolytic enzymes except phenol oxidase and peroxidase activities. The carbon management index under ZTWRS100 retained was significantly higher than zero-till or conventional till wheat without residue. The principal component analysis identified active carbon, less labile carbon pools; xylanase and dehydrogenase hydrolytic enzymes as the most reliable sensitive indicators for assessing soil quality for conservation agriculture (CA) – based practices in RWS. The study showed that adoption of PTR with 25%-anchored wheat stubbles retained plus GM in rice followed by ZTWRS100 in wheat was the best crop production strategy for enhanced carbon pools, hydrolytic enzymatic activities and gives an idea of its overall fitness for carrying out ecosystem functions.

Agricultural productivity relies on a wide range of ecosystem services provided by the soil biota. Sustainable management practices, such as tillage and residue management, can influence structure and function of the soil microbiota, with direct consequences for the associated ecosystem services. Although there is increasing evidence that different tillage regimes alter the soil biological indices, we only have a limited understanding of their temporal changes in a rice (Oryza sativa L.)-wheat (Triticum aestivum L.) cropping system. We evaluated the effects of combinations of tillage, crop residue management and green manuring on soil biological indicators after 5 years of the practising rice-wheat system (RWS). Four main plot treatments in rice included the following: (a) PTRW0, puddled transplanted rice with no wheat straw retained; (b) PTRW25, puddled transplanted rice with 25% anchored wheat stubbles retained; (c) PTRW0 + Sesbania aculeate L. green manure (GM); and (d) PTRW25+GM, puddled transplanted rice with 25% anchored wheat stubbles retained+ GM. There were three subplot treatments in the subsequent wheat crop: (a) CTWR0, conventional tillage wheat with rice residue removed; (b) ZTW(R)(0), zero tillage wheat with rice residue removed; and (c) ZTW(R)(100), ZTW with 100% rice residue retained as mulch. The PTRW25+GM treatment, followed by ZTW(R)(100), significantly increased soil microbial biomass carbon, basal soil respiration, microbial quotient and mineralization quotient measured during wheat-growing season. These biological indicators were higher at vigorous vegetative wheat growth stage than at flowering stage and decreased at maturity. The principal component analysis of the assayed variables showed that all the variables significantly contributed to the variability in parameters examined and were more related to maximum tillering stage of wheat growth than to maturity or at sowing of wheat. Three highly effective biological indicators were microbial biomass carbon, microbial quotient and mineralization quotient, which responded significantly to changes in tillage and residue management practices in the RWS. We conclude that crop residues and green manure have significant to improve soil biochemical processes by improving soil organic carbon and soil biological indicators in rice-wheat cropping system.

A field experiment was conducted to assess the effect of straw mulching and irrigation scheduling on water balance, economics and energetics of potato during 2013–2014 and 2014–2015. The experiment was laid out in a split plot design with mulch levels (no mulch and mulch 6.25 t ha−1) in the main plots and four irrigation schedules {ridge planting furrow irrigation (RPFI), bed planting furrow irrigation (BPFI), ridge planting drip irrigation (RPDI) and bed planting drip irrigation (BPDI)} in the subplots. Straw mulching resulted in 19.0% higher potato tuber yield than no mulch as a result of 36.2 mm higher transpiration and 44.2 mm lower soil evaporation. Energy productivity (EP) and energy use efficiency (EUE) were also significantly higher with straw mulch than no mulch with US$498 ha−1 higher net returns in pooled data of both years. Drip irrigation of beds and ridges resulted in 34.9% and 26.4% higher tuber yields, respectively, than furrow irrigation along with savings of 23.3 and 53.3 mm irrigation water, respectively. Seasonal transpiration was 31.0 and 31.7% higher in ridge- and bed-planted drip-irrigated crops, respectively, than furrow-irrigated crops in pooled data. Apparent and real water productivities were significantly higher in drip irrigated crops compared to furrow irrigated crops. RPDI and BPDI crops gave US$612 and US$876 ha−1 higher net returns with 35.7 and 28.8% higher EUE than RPFI and BPFI, respectively.

Soil quality degradation in the last four decades is threatening the sustainability of puddled transplanted rice (Oryza sativa L.) wheat (Triticum aestivum L.) (RW) system in north-western region of India. Hence comprehensive information on the influence of soil and crop management practices in intensive and nutrient exhausting RW system on soil quality is urgently needed. The present study evaluated the effects of crop residues, green manure and tillage on the changes in soil biochemical properties at different growth stages of wheat after five cycles of RW system. Four main plot treatments in rice included combinations of wheat straw and Sesbania green manure management: (1) PTRWSO, puddled transplanted rice (PTR) with no wheat straw (2) PTRWS25, puddled transplanted rice with 25% anchored wheat stubbles retained (3) PTRWSO plus green manure (GM), and (4) PTRWS25 plus GM. Three sub-plots treatments in subsequent wheat included (1) CTWRS0, conventional tillage wheat without rice straw (2) ZTW(RS0), zero tillage wheat without rice straw and (3) ZTW(RS100), ZTW with 100% rice straw retained as surface mulch. The results showed that PTRWS25 plus GM and ZTW(RS100) increased significantly all the soil biochemical properties (enzyme activities and glomalin related soil protein concentration) except phenol oxidase and peroxidase activities. The activities of dehydrogenase, beta-glucosidase and concentration of easily extractable glomalin and total carbohydrate carbon under ZTW(RS100) were 36.8, 24.6, 25.9 and 23.3% higher than CTWRS0. Application of GM and wheat straw retention in previous rice significantly increased grain yield of subsequent wheat crop by 26.5%. The majority of the increases in biochemical properties were higher at vegetative growth (at 40-45 days after sowing) and flowering (at 80-85 days after sowing) stages compared to the initial and at maturity. Principal component analysis identified beta-glucosidase, cellulase and phenol oxidase activities as the most sensitive and reliable indicators for assessing soil quality for conservation agriculture based RW system.

Enhancing soil organic carbon (SOC) is an important strategy to sustain and improve the soil quality, mitigate climate change and increase crop productivity under intensive tillage-based rice–wheat (RW) system in the Indo-Gangetic Plains (IGP) of South Asia. Therefore, the effects of tillage, crop establishment, and residue management practices on total as well as different pools of SOC in a sandy loam after 6 years of RW system were studied. The imposed three main plot treatments to the rice plots were: (1) ZTDSR, zero till dry seeded rice; (2) CTDSR, conventional till dry seeded rice; and (3) PTR, conventional puddled transplanted rice, and the three sub-plot treatments in succeeding wheat were (i) CTW − R, conventional tillage (CT) wheat with both rice and wheat residues removed; (ii) ZTW − R, zero tillage (ZT) wheat with both the residues removed and (iii) ZTW + R, ZT wheat with rice residue. Total soil organic content increased by 6.5–12.5% and 3.1–12.9% in different soil layers up to 0–60 cm depth in ZTDSR followed by ZTW + R over PTR followed by CTW − R practices, respectively. The corresponding increase of the oxidizable C was 4.2–28.2% and 8.2–8.5%, respectively. Significant enhancement in all the carbon pools (non-labile, less labile, labile, very labile pools, water soluble and microbial biomass carbon) and glomalin content were also recorded in ZTW + R treatment. The carbon management index was significantly higher in ZTW + R than ZTW − R and CTW − R treatments. In conservation-based agriculture systems, the principal component analysis revealed that passive pools of SOC and microbial biomass carbon were the most promising and reliable indicators for assessing soil quality. This study showed that adoption of ZTDSR followed by ZTW + R was the better crop production strategy for increasing C-sequestration, improving and sustaining the soil quality and crop productivity in the RW system. This practice also provides an opportunity to retain crop residues as an alternative to burning, which causes severe air pollution in the RW system in the IGP of South Asia.

The rice–wheat system (RWS) practiced in northwestern parts of the Indo-Gangetic plains of India is highly productive, but conventional practices are resource (water, labour and energy) and cost intensive. A 4-year field study evaluated the effects of green manure (GM), crop residue and tillage on crop yields, economic profitability and soil fertility in a RWS. Four main plot treatments in rice included combinations of wheat stubble and Sesbania aculeata GM management: (1) puddled transplanted rice (PTR) with no wheat stubble, (2) PTR with 25% wheat stubbles (15–20 cm high) retained, (3) PTR with no wheat stubble plus GM, and (4) PTR with wheat stubble splus GM. Three sub-plots treatments in subsequent wheat included (1) conventional till wheat with rice straw removed (CTWR0), (2) zero till wheat with rice straw removed (ZTWR0) and (3) zero till wheat with 100% rice straw retained as surface mulch (ZTWR100). The results showed that main rice yield was significantly higher (8.0%) with 50% less fertilizer N application in GM compared with conventional PTR with no GM. Rice treatments did not affect the grain yield of subsequent wheat. ZTWR100 produced significantly higher mean wheat grain yield by 7.3% and 17.5% compared with CTWR0 and ZTWR0, respectively. System productivity was 11.5% higher in PTR with wheat stubble + GM followed by ZTWR100 compared with the conventional RWS and resulted in Rs 24,075 ha−1 more net returns. Significant increases in soil organic carbon, available P and available K contents were recorded in ZTWR100 over CTWR0. Recycling rice and wheat stubble in the field in RWS is also environment friendly as it avoids ill effects of straw burning.

Decline in soil organic carbon (SOC) due to intensive tillage and removal or burning of crop residues is considered a major threat to maintaining soil quality and meeting future challenges of food production at national and global scales. Adoption of conservation-agriculture practices (no till and residue retention) is necessary to promote soil structural stability and increases in SOC content and enzyme activities. We evaluated the impact of tillage and residue-management practices on yield, soil labile-C pools, aggregate stability and soil enzyme activities after seven cycles of a rice (Oryza sativa L.)–wheat (Triticum aestivum L.) system on the Indo-Gangetic Plain of India. Treatments included four combinations of tillage and crop establishment in rice (main plots), and three combinations of tillage and residue management in wheat (subplots). Irrespective of rice-establishment method, mean grain yield of no-till wheat with rice-residue mulch (NTW+RR) was 9% and 22% higher, respectively, than of conventional-till (CTW) or no-till wheat with no rice-residue mulch. Soil C pools (very labile, labile, less-labile and non-labile) were significantly higher under a no-till dry-seeded rice (NTDSR)–NTW+RR cycle than conventional-till puddled transplanted rice–CTW. Macro-aggregates (>0.25 mm) had higher labile C pools, glomalin content and enzyme activities than micro-aggregates. NTW+RR significantly increased soil C pools within both macro- and micro-aggregates. Compared with CTW, NTW+RR increased soil dehydrogenase, cellulase and alkaline phosphatase activities by 23%, 34% and 14%, and water-soluble organic C by 31%, and increased water-stable aggregates and mean-weight-diameter. NTDSR–NTW+RR increased SOC, enzyme activity, aggregate stability and wheat grain yield. Results indicated that soil labile-C pools across aggregate fractions were the most sensitive indicators of soil quality when determining the effects of changes in management practices. Furthermore, adoption of no till and residue retention may improve sustainability in rice–wheat systems of the Indo-Gangetic Plain.

The traditional flood irrigation system has led to overexploitation of ground water and low nitrogen (N) use efficiency. In north-western India, maize-based systems with lower irrigation requirement are being advocated as an alternate to rice-based systems to address the issues of declining water table. Bed planting of crops, straw mulching and drip irrigation are known to save precious irrigation water, and improve N use efficiency and grain yields. To this effect a two-year field experiment was conducted with annual wheat-maize rotation on permanent bed system to evaluate the effect of surface drip irrigation, residue management, and N application on crop and water productivity. Maize and wheat under drip irrigation with residue retention system showed significant grain yield increase of 13.7% and 23.1% compared to furrow irrigation with no residue, respectively. Surface drip irrigation with residue retention saved 88 mm and 168 mm of water and increased water productivity by 66% and 259% in wheat and maize on permanent beds compared to the conventional furrow irrigation system with residue removal, respectively. Similarly, fertigation at 10-day interval with five splits in wheat and seven splits in maize under drip irrigation system increased the mean N recovery efficiency by 16.5% and 29% compared to furrow irrigation in wheat and maize, respectively.

Dry direct-seeded aerobic rice (DSR) is an emerging attractive alternative to traditional puddled transplanted rice (PTR) production system for reducing labour and irrigation water requirements in the Indo-Gangetic plains (IGP) of India. The fertilizer N requirement of DSR grown with alternate wetting and drying water management may differ from that of PTR grown under continuous flooding due to differences in N dynamics in the soil/water system and crop growth patterns. Limited studies have been conducted on optimizing N management and application schedule for enhanced N use efficiency in DSR. Therefore, field experiments were conducted over 3years in NW India to evaluate the effects of N rate and timing of its application on crop performance and N use efficiency. Interaction effects of four N rates (0, 120, 150, and 180kg ha(-1)) as urea and four schedules of N application on yield and N use efficiency were evaluated in DSR. The N schedules included N application in three equal split doses (0, 35 and 63, and 14, 35 and 63days after sowing, DAS) and four equal split doses (0, 28, 49 and 70; 14, 28, 49 and 70 DAS). There was no significant interaction between N rate and schedules on grain yield. Significant response to fertilizer N was observed at 120kg N ha(-1) and economic optimum dose for three equal split doses and skipping N at sowing was 130kg N ha(-1). Highest mean grain yield of 6.60t ha(-1) was obtained when N was applied in three equal split doses at 14, 35 and 63 DAS which was about 8.5% higher compared with N applied in four equal split doses at 14, 28, 49 and 70 DAS. Under the best N application schedule, agronomic N use efficiency (26kg grain kg(-1)), recovery efficiency (49%) and physiological efficiency (53kg kg(-1)) were comparable to the values reported in Asia for PTR. Results from our study will help to achieve high yields and N use efficiency in DSR to replace resource intensive PTR.

Intensive tillage, removal or burning of crop residues, limited organic manure use, declining irrigation water resources and scarcity of labour are the major causes of soil degradation and unsustainability of rice (Oryza sativa L.)–wheat (Triticum aestivum L.) system (RWS) in South Asia.Resource conservation technologies (RCTs) such as zero tillage (ZT), dry direct seeded rice (DSR) and crop residues retained as mulch have shown promise to increase the productivity and profitability of RWS in South Asia. Effects of RCTs on soil biological parameters are unclear and contradictory. We evaluated the effects of conservation agriculture practices on changes in soil biochemical properties at different growth stages of wheat grown as the fifth crop in RWS. Twelve treatment combinations of tillage, crop establishment and crop residue management included four main plot treatments in rice: (1) conventional tillage (CT)-DSR,(2) ZT-DSR, (3) DTR, ZT machine transplanted rice and (4) PTR, conventional puddled transplanted rice. The three subplot treatments were: (i) CTW-R, CT wheat with both rice and wheat residues removed, (ii) ZTW-R, ZT wheat with residues of both the crops removed and (iii) ZTW+R, ZT wheat with rice residue retained as surface mulch in subsequent wheat. Irrespective of rice establishment methods, mean wheat grain yield under ZTW+R was 6% and 10% greater than CTW-R and ZTW-R respectively. Soil enzyme activities increased (5–18%) under ZTW+R compared with ZTW-R and CTW-R at different growth stages of wheat. The residual effect of rice establishment methods was significant on soil enzyme activities during wheat cropping, which were highest under ZT-DSR followed by CT-DSR, DTR and PTR. Soil organic carbon content in the 0–7.5 cm layer was significantly higher (7–9%) under the ZTW+R treatment compared with all the other treatments. Principal component analysis (PCA) identified three enzyme activities (dehydrogenase, fluorescein diacetate and phosphatase), and soil organic carbon content as the most sensitive indicators for assessing soil quality for RWS based on conservation agriculture. The PCA discriminated rice establishment systems with rice residue as surface mulch from rice establishment systems without rice residue and the maximum tillering stage from the other stages of wheat. The present study provided reliable biochemical indicators to monitor soil biological quality changes in response to conservation agriculture practices in RWS.

Soil microbes play critical roles in soil biogeochemistry, soil biological health and crop productivity. The current study evaluated the effects of tillage and residue management on changes in soil biochemical indicators at different growth stages of wheat after 5 years of rice-wheat system. Nine treatment combinations of tillage, crop establishment and crop residue management included three main plot treatments applied to rice:（1） conventional till direct dry seeded rice（CTDSR）,（2） zero till direct dry seeded rice（ZTDSR）, and（3） conventional puddled manual transplanted rice（CTPTR） and three subplot treatments in subsequent wheat:（1） conventional tillage with rice residue removed（CTW-R）,（2） zero tillage with rice residue removed（ZTW-R） and（3） zero tillage with rice residue retained as surface mulch（ZTW+R）. Irrespective of rice treatments, ZTW+R treatment had higher soil biochemical indicators compared with ZTW-R and CTW-R at all the growth stages of wheat. Generally, all the biochemical indicators were the highest at the flowering stage of wheat. Residual effect of rice treatments was also significant on biochemical quotients in wheat, which were the highest under ZTDSR followed by CTDSR and CTPTR. The present study provided three sensitive and reliable biochemical indicators（microbial biomass, basal soil respiration and microbial quotient） which respond rapidly to change in tillage and residue management practices in RWS of South Asia.

In irrigated wheat as grown in north-western India, fertilizer nitrogen (N) management following blanket recommendations is increasing resulting in stagnant yield levels with low N use efficiency. Site-specific nutrient management strategy to apply N as per need of wheat crop was formulated based on leaf colour measured by chlorophyll meter (Minolta SPAD meter) as a function of soil N supply. The SPAD meterguided protocols for fertilizer N application at crown root initiation (CRI) and maximum tillering (MT) stages, coinciding with first two irrigations, were evaluated through a series of field experiments with seven wheat varieties in Ludhiana and Gurdaspur in north-western India. Threshold leaf greenness levels equivalent to SPAD readings <40, <42.5 and <45 were tested in terms of (i) whether to apply fertilizer or not, and (ii) deciding as to how much fertilizer N needs to be applied as per requirement of the crop. At CRI stage, when the crop was about two-week old, fertilizer N dose could not be guided by SPAD meter because due to application of a basal dose of N at planting variation in the leaf colour was found to be very small. Also, due to small size of leaves at CRI stage it was difficult to use SPAD meter to measure leaf colour. Application of 30 kg N ha−1 at planting, 45 kg N ha−1 at CRI stage and a dose of 30 or 45 kg N ha−1 at MT stage depending upon leaf greenness to be ≥ or < SPAD 42.5, respectively produced wheat grain yields at par with blanket recommendation for fertilizer N, but with higher fertilizer N use efficiency.

Disposal of ashes from agro-industrial waste has become an important issue that can cause serious environmental problems. These materials may be used in agriculture for soil fertility improvement and carbon sequestration. The effect of applying bagasse ash (BA), rice husk ash (RHA), and RHA mixed with fly ash (MA) to wheat was evaluated on soil organic carbon (SOC) and microbial activity in a loamy sand soil after four years of wheat-rice cropping. BA application resulted in C accrual at 525 kg ha(-1) y(-1) in soil, whereas RHA and MA did not have a significant effect. BA increased coarse particulate (cPOC) and mineral-associated organic matter (MinOC) and extractable C pools viz. hot water soluble, potassium permanganate (KMnO4)-oxidizable, easily oxidizable, non-oxidizable, and microbial biomass C. BA application also improved overall microbial and oxidative activity and stimulated fluorescein diacetate (FDA), dehydrogenase, and cellulase enzyme activities in soil. Application of RHA though did not lead to net C sequestration, yet it increased dehydrogenase and cellulase activities. Compared to unamended soil, MA application increased MinOC and FDA activity in soil. After 4 years of their application, none of the ashes adversely influenced soil biological activity expressed in terms of enzyme activities suggesting that these ashes can be disposed to agricultural soils. However, effects of their long-term application on soil biological processes need to be further investigated.

Site-specific fertilizer nitrogen management (SSNM) could be the best management option to avoid excessive and untimely nitrogen (N) applications in wheat. Field experiments were conducted in soils of varying inherent fertility in diverse agro-climatic zones to provide SSNM strategy for wide range of wheat genotypes. The intensity of leaf colour greenness of the first fully exposed top leaf was measured using leaf colour chart (LCC) and chlorophyll meter (SPAD) at different growth stages. The spectral properties of leaves at different growth stages differed among the different wheat genotypes except at Feekes 6 stage, thus the leaf greenness measured only at this stage can be used to make SSNM decisions. After applying 25 kg N ha−1 at planting and 45 kg N ha−1 at Feekes 2 stage, the leaf greenness of the first fully exposed top leaf measured with LCC at Feekes 6 stage was used to decide the amount of site-specific fertilizer N to be applied as topdressing. The LCC guided fertilizer N dose sustained grain yield to the level as obtained with soil test based N applications with the less use of 20–50 kg N ha−1. The practice of applying additional N or just increasing number of split doses in soils with low Walkley–Black organic carbon content may not improve grain yield unless plants really need it. The SSNM strategy improved agronomic efficiency of applied fertilizer N in different wheat genotypes grown under diverse range of agro-climatic conditions and in soils with variable indigenous N supply.

An optical sensor-based fertilizer nitrogen (N) management strategy that relies on visible and near-infrared spectral response from plant canopies was evaluated for irrigated wheat in the northwestern India. GreenSeeker™ optical sensor-guided fertilizer N dose, computed from an estimate of potential yield and response index, takes into account both the temporal and field-to-field variabilities and is applied only once after measuring in-season spectral response from the crop canopy. Seven field experiments were conducted in four wheat seasons to decide whether to apply the optical sensor-guided fertilizer N dose at 2nd or 3rd irrigation stage and to work out the appropriate N management before applying it. Robust relationships between in-season sensor-based estimates of yield and actual wheat yields were observed both at 2nd (R 2 = 0.64) and 3rd (R 2 = 0.86) irrigation stages of the crop. GreenSeeker-based fertilizer N management resulted in high yield levels and high N-use efficiency. Application of 30 kg N ha−1 at planting and 45 kg N ha−1 at 1st irrigation was found to be the appropriate N management before applying the GreenSeeker-guided dose at 2nd irrigation stage. Grain yields obtained by following sensor-guided N management were at par with those observed with the blanket recommendation of 120 kg N ha−1, but with greater recovery efficiency (by 6.7–16.2%) and agronomic efficiency [by 4.7–9.4 kg grain (kg N applied)−1]. The major outcome of this study was that applying a moderate amount of fertilizer N at planting and enough fertilizer N to meet the high N demand during the period between crown root initiation stage and maximum tillering stage before applying a sensor-guided fertilizer N dose at 2nd irrigation stage results not only in high yields but also in high fertilizer N-use efficiency in irrigated wheat.

Conservation agriculture is a potential solution for increasing yield in wheat crop in the rice wheat cropping system. A study was carried out to assess the impact of the conservation practices in rice-wheat cropping system. The experiment was conducted at the PAU, Ludhiana during 2010-2013. The design of an experiment was split-plot with 12 treatments and 3 replications. The main plot treatments of rice (zero till direct seeded rice, ZT-DSR; conventional till direct seeded rice, CT-DSR; zero till direct transplanted rice, ZT-DTR and puddled transplanted rice, PTR) and sub-plot treatments of wheat (conventional till wheat without rice straw, CTW-R; ZT wheat without rice straw, ZTW-R, and ZT wheat with rice straw retained as surface mulch using Happy Seeder, ZTW+R). The treatment ZTW+R recorded significantly higher grain yield (5.26 t ha-1) than other treatments. The yield attributes viz., 1000 grain weight, spike length, grain weight per spike and grains per spike were significantly higher in ZTW+R than that of ZT/CT with no straw. Significantly higher macronutrients (N, P and K) and micronutrients (Zn, Fe, Mn and Cu) uptake were recorded under ZTW+R compared with ZT/CT without rice straw. The study recommended that the conservation agriculture practices will gives better soil environment for crop growth and development which may be responsible for enhancement of grain yield and nutrient uptakes.

Ashes from agricultural biomass in agro-based industries have been found to have most of the plant nutrients except nitrogen and sulphur but are treated as waste material. The present study was conducted to evaluate the potential of biomass ashes as source of P and their effect on bioavailability of micronutrients in wheat crop. We conducted the pot experiment at glass house of the Department of Soil Science, Punjab Agricultural University, Ludhiana, India. The experiment consisted of combinations of four P sources [bagasse ash (BA), rice husk ash (RHA), rice straw ash (RSA), fertilizer P (Fert-P)] supplying P at three levels (10, 20 and 30 µg g-1) along with one zero-P control. This experiment was laid out in completely randomized design (CRD) having three replications. Application of P through RSA produced significantly higher grain yield (14.3 g pot-1) than BA (12.8 g pot-1) and RHA (12.9 g pot-1) but statistically at par with Fert-P (13.5 g pot-1). Grain Zn content decreased maximum than other micronutrients with application of P from all sources, hence maximum increased P/Zn ratio. Phosphorus applied from all the biomass ashes significantly increased biomass and yield over control. With increase in P application, micronutrients content in grain was significantly decreased, hence decreased bioavailability of micronutrients in wheat grain.

A long-term field experiment was conducted for 7 years to evaluate the effect of different amendments to mitigate the adverse effect of saline-sodic water in a calcareous soil under cotton-wheat cropping system. The pooled results over 7 years revealed that the application of saline-sodic water decreased the mean cotton-seed yield by 20.7% as compared to good quality canal water. However, wheat-grain yield was not adversely affected by quality of irrigation water. Among the different amendments, gypsum and farmyard manure were more effective in mitigating the adverse effect of saline-sodic irrigation water. Cotton-seed yield reduction was 9.8% with the addition of farmyard manure and remained only 8.8% with the addition of gypsum as compared to good quality water. However, when saline-sodic water was used alternately with good quality canal water, the recorded cotton-seed yield reduction was only 6.1%. These results suggest that in calcareous soils, farmyard manure is useful in ameliorating long-term deleterious effects of saline sodic irrigation water and sustaining the productivity of cotton-wheat system.