Effect of conjoint use of bio-organics and chemical fertilizers on yield,soil properties under French bean–cauliflower-based cropping system

This study investigates the effect of conjoint use of bio-organics (biofertilizers + crop residues + FYM) and chemical fertilizers on yield, physical–chemical and microbial properties of soil in a ‘French bean–cauliflower’-based cropping system of mid hills of the north-western Himalayan Region (NWHR) of India. Conjoint bio-organics at varied levels of NPK chemical fertilizers increased yield of ‘cauliflower’ over corresponding single application. Incorporation of crop residues with 75% of the recommended NPK application resulted in the highest yield (19 t ha^?1). Conjoint use of bio-organics produced a yield (15.65 t ha^?1), which was statistically on a par with 75% of the recommended NPK application alone. This indicated a saving of 75% NPK chemical fertilizers. In the case of ‘French bean’, the effect was non-significant. The results also showed significant higher soil available N (351.3 kg ha^?1) under 75% NPK + biofertilizers, whereas the highest soil available K (268.3 kg ha^?1) was recorded under 75% NPK + crop residues. Lowest bulk density (1.03 Mg m^?3), highest water holding capacity (36.5%), soil organic matter (10.6 g kg^?1), bacterial (4.13 × 10⁷ cfu g^?1) and fungal (6.3 × 10⁷ cfu g^?1) counts were recorded under sole application of bio-organics. According to our study, we concluded that the combination of NPK fertilizers and bio-organics increased yield except French bean, soil available N, K and saved chemical fertilizers under ‘French bean–cauliflower’-based cropping system.     

Amelioration of saline–sodic soil with gypsum can increase yield and nitrogen use efficiency in rice–wheat cropping system

A 2-year field experiment was conducted to determine crop yield and N use efficiency (NUE) from a saline–sodic soil (clay loam) with and without application of gypsum. Treatments included two N application rates (15% and 30%) higher than the recommended one to the normal soil, and gypsum added at 50% and 100% of soil gypsum requirement (SGR) to the saline–sodic soil, both cultivated with rice and wheat during 2011–2013. Results revealed a decrease in pH of saturated soil paste (pH_s), electrical conductivity of saturation extract (EC_e), sodium adsorption ratio (SAR) and exchangeable sodium percentage with N fertilizer along with gypsum application in saline–sodic soil. However, the effect was most prominent when gypsum was added at 50% of SGR. Crop yield and NUE remained significantly lower (p < 0.05) in saline–sodic-soils as compared to normal soil. However, gypsum application reduced this difference from 47% to 17% since both yield and NUE increased considerably. Crop yield and NUE remained higher for wheat than for rice. During first year, higher doses of N with gypsum application at 50% SGR proved most effective, whereas, in subsequent year, recommended N along with gypsum at 50% SGR became more profitable. All these results lead us to conclude that gypsum application can ameliorate saline–sodic soil thereby increasing crop yield and NUE.     

Influence of summer legume residue recycling and varietal diversification on productivity,energetics, and nutrient dynamics in basmati rice–wheat cropping system of western Indo-Gangetic Plains

A field experiment was conducted on summer mungbean residue recycling (SMBRR) and basmati rice–wheat cropping system (BRWCS) at New Delhi, India. The SMBRR enhanced the system productivity and net returns by ～19.1% and 22.1% compared to summer fallow (SF) with highest magnitude under genotypic sequence of P 2511/HD 2967. Two genotypes each in basmati rice (PB 1 and P 2511) and wheat (HD 2967 and HD 2733) responded well to SMBRR with respect to grain yield efficiency index (GYEI) ≥ 1.0. SMBRR also registered ～13.5% higher microbial biomass carbon (MBC) than SF. Soil organic carbon (SOC) storage also increased by ～6.8% in 0–30 cm soil layer. The rice–wheat–summer mungbean system produced significantly highest energy efficiency compared to the rice–wheat–summer fallow system with highest values under genotypic sequence of P 2511/HD 2967 as a result of better yield expression. Overall, SMBRR with suitable genotypic sequence improved the system productivity, profitability, and nutrient dynamics in BRWCS, which are vital for long-term sustainability of this system.     

Long-term manuring and fertilization influence soil inorganic phosphorus transformation vis-a-vis rice yield in a rice–wheat cropping system

A study on the rice–wheat cropping system was conducted at Bidhan Chandra Krishi Viswavidyalaya, West Bengal, India, to assess the effects of long-term manuring and fertilization on transformation of the inorganic phosphorus (P) fraction in soil after 22 years of the crop cycle. Soil samples were collected after Kharif from seven treated plots having different types of organic amendments like farm yard manure, paddy straw and green manuring with 50% substitution of nitrogen levels in rice crop only. The result showed that the yield trend of rice was maintained due to the buildup of P from various organic inputs. Although cultivation for 22 years without adding any fertilizer caused a significant decrease in almost all the forms of P viz. avail-P, saloid P, iron phosphorus fraction (Fe–P), aluminum phosphorus fraction (Al–P), calcium phosphorus fraction (Ca–P) and total P in control. Partial substitution of inorganic fertilizer N (50%) with organics, however, caused a significant increase in almost all the P fractions in soil over the control. The relative abundance of all the fractions of inorganic P irrespective of treatments was as follows: Fe–P > reductant soluble P fraction > occluded P > Al–P > Ca–P > saloid P. Saloid and Fe–P were the dominating fractions responsible for 92% variation of available P and total P levels, respectively.     

Effect of nutrient management and straw mulching on crop yield,uptake and soil fertility in rapeseed (Brassica campestris)–greengram (Vigna radiata)–rice (Oryza sativa) cropping system under Gangetic plains of India

An experiment was conducted at Bidhan Chandra Krishi Viswavidyalaya, West Bengal, India during 2001–2003 to study the effect of levels of fertility and straw mulch on a rapeseed (Brassica campestris var yellow sarson)–greengram (Vigna radiata)–rice (Oryza sativa) cropping system under a rainfed upland ecosystem. The experiment was laid out in a split-plot design having 14 treatment combinations of organic and inorganic nutrients along with straw mulch in three replicates. The results revealed that conjunctive use of organic and inorganic nutrients as well as paddy straw mulch resulted higher yield in both rapeseed and greengram, and the residual effects of different levels of fertilization and mulching also gave rise to higher grain yield in the succeeding rice crop. The uptake of nutrients, by the cropping system as a whole, to the tune of 204.29 and 183.00 kg ha^?1 of N, 72.84 and 74.07 kg ha^?1 of P and 179.95 and 175.41 kg ha^?1 of K took place, with the treatment receiving 10 t ha^?1 of farmyard manure (FYM) applied (to rapeseed) along with 50% recommended dose (RD) of NPK to all the crops in the sequence in two consecutive years, respectively. The same treatment resulted in a higher percentage of porosity vis-à-vis lower bulk density. Soil physico-chemical properties were superior in mulch-treated plots compared with no mulch treatment. Application of organic and inorganic nutrients along with proper moisture conservation practices can enhance the yields maintaining a good soil health.     

Effect of 46 years' application of fertilizers,FYM and lime on physical,chemical and biological properties of soil under maize–wheat system in an acid Alfisol of northwest Himalayas

Imbalanced fertilizer use with intensive cropping has threatened the sustainability of agroecosystems, especially on acid soils. An understanding of the long-term effects of fertilizers and amendments on soil health is essential for sustaining high crop yields. The effects of application of fertilizers, and amendments for 46 years on soil properties and maize yield in an acid Alfisol were investigated in this study. Ten fertilizer treatments comprising different amounts of NPK fertilizers, farmyard manure (FYM) and lime, and one control, were replicated three times in a randomized block design. At 0–15 cm soil depth, bulk density was least (1.20 t/m³), porosity (49.8%) and water holding capacity (61.7%) were greatest in 100% NPK + FYM, corresponding to the largest organic carbon content (13.93 g/kg). Microbial biomass C and dehydrogenase activity in 100% NPK + FYM were 42% and 13.7% greater than 100% NPK, respectively. Available nutrients were significantly more with 100% NPK + FYM and 100% NPK + lime than control and other fertilizer treatments. At 15–30 cm depth, the effect of various treatments was comparable to the surface layer. Grain yield declined by 55% and 53% in 100% NPK(-S) and 100% NP, respectively, compared with 100% NPK, whereas 100% N as urea alone eventually led to crop failure. Soil porosity recorded the greatest positive correlation (r = .933**), whereas bulk density recorded a negative significant correlation (r = −.942**) with grain yield. The results suggest that integrated use of FYM/lime with chemical fertilizers is a sustainable practice in terms of crop yield and soil health, whereas continuous application of urea alone is detrimental to the soil health.     

Tillage and residue management practices affect soil biological indicators in a rice–wheat cropping system in north-western India

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) PTR_W0, puddled transplanted rice with no wheat straw retained; (b) PTR_W25, puddled transplanted rice with 25% anchored wheat stubbles retained; (c) PTR_W0 + Sesbania aculeate L. green manure (GM); and (d) PTR_W25+GM, puddled transplanted rice with 25% anchored wheat stubbles retained+ GM. There were three subplot treatments in the subsequent wheat crop: (a) CTW_R0, conventional tillage wheat with rice residue removed; (b) ZTW_R0, zero tillage wheat with rice residue removed; and (c) ZTW_R100, ZTW with 100% rice residue retained as mulch. The PTR_W25+GM treatment, followed by ZTW_R100, 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.     

Biochar use in a legume–rice rotation system: effects on soil fertility and crop performance

The aim of this study was to determine whether by applying biochar, it is possible to augment the beneficial effects of legume–crop rotation systems on soil fertility and crop performance. Repeated experiments were established in 2012 and 2013 in South-western Benin using a split-split plot design. Two legumes, Mucuna pruriens (mucuna) and Vigna unguiculata (cowpea), were planted for 42 days on biochar-amended and unamended plots and subsequently cut and applied as mulch 5 days before planting rice. Rice plants were either fertilized or not using a fertilizer rate of 60, 30, and 30 kg ha^?1 of N, P₂O₅, and K₂O, respectively. The results showed that the application of legume green manures and fertilizer, either singly or in combination, improved soil nutrient availability, CEC, shoot yield, and grain yield of rice on both biochar-amended and unamended plots. However, the effect was significantly (p < 0.05) greater on biochar-amended plots. The mean grain yield for all cropping seasons was 1.8 t ha^?1 for biochar-amended plots and 1.3 t ha^?1 for unamended plots. The greater grain yield of rice on biochar-amended plots was associated with improved soil fertility and increased N uptake.     

Evaluation of press mud cake as a source of nitrogen and phosphorus for rice–wheat cropping system in the Indo-Gangetic plains of India

Press mud cake (PMC) is an important organic source available for land application in India. Adequate information regarding availability of nitrogen and phosphorous contained in PMC to rice–wheat (RW) cropping system is lacking. In field experiments conducted for 4 years to study the effect of PMC application to rice as N and P source in RW system, application of 60 kg N ha⁻¹ along with PMC (5 t ha⁻¹) produced grain yield of rice similar to that obtained with the 120 kg N ha⁻¹ in unamended plots. In the following wheat, the residual effects of PMC applied to preceding rice were equal to 40 kg N and 13 kg P ha⁻¹. Immobilization of soil and fertilizer N immediately after the application of PMC was observed in laboratory incubation. The net amount of N mineralized from the PMC ranged from 16% at 30 days to 43% at 60 days after incubation. Available P content in the soil amended with PMC increased by about 60% over the unamended control within 10 days of its application. The P balance for the no-PMC treatment receiving recommended dose of 26 kg P ha⁻¹ year⁻¹ was −13.5 kg P ha⁻¹ year⁻¹. The P balance was positive (+42.3 to 53.5 kg P ha⁻¹ year⁻¹) when PMC was applied to rice. Application of PMC increased total N, organic carbon, and available P contents in the soil.     

Poultry litter as a nitrogen and phosphorous source for the rice–wheat cropping system

Poultry litter (PL) is an important nutrient source; however, no information is available regarding its value in supplying N and P in rice–wheat (RW) production. A three-year field study was conducted at Ludhiana, Punjab, India on a loamy sand soil to identify optimum combination of PL and N and P fertilizers for a sustainable RW production. The litter was applied to rice at 5 Mg ha⁻¹ as a single application and supplemented with different rates of N. The residual effect of PL and the direct effects of the different combinations of N and P were studied in the following wheat. Nitrogen and P mineralization from PL was studied under controlled conditions in the laboratory, and macronutrient input–output balances were estimated from field results. About 46% of the N from PL was released after 60 days of incubation. The release of P from the PL occurred mainly during the initial 20 days after incubation, accounting for 15–17% of the total P. Combining PL with fertilizer N (40 kg ha⁻¹) increased rice yield and nutrient uptake similar to what was obtained with the application of recommended fertilizer N (120 kg ha⁻¹). In the following wheat, the residual effect of PL was equal to 30 kg N ha⁻¹ and 13 kg P ha⁻¹. After three annual cropping cycles and PL application, mean soil organic C increased by 17%, Olsen-P by 73%, and NH₄OAc-extractable-K by 24%. Most treatments had positive P but negative K balances. About 11% of the net P balance was recovered from the soil as Olsen-P. The study showed that optimum N and P fertilizer doses for an RW system receiving 5 Mg ha⁻¹ of PL are 40 kg N ha⁻¹ for rice and 90 kg N + 13 kg P ha⁻¹ for the following wheat. Safe and effective management of PL should be based on P balance, particularly when regular applications of PL are to be made in the RW system.     

Influence of Azospirillum inoculation and nitrogen supply on grain yield,and carbon‐ and nitrogen‐assimilating enzymes in maize

Nitrogen (N) supply increased yield, leaf % N at 10 days after silking (DAS) and at harvesting, the contents of ribulose‐1,5‐bisphosphate carboxylase (RUBISCO) and soluble protein, and the activities of phosphoenolpyruvate carboxylase (PEPC), and ferredoxin‐glutamate synthase (Fd‐GOGAT), but not of glutamine synthetase (GS) for six tropical maize (Zea mays L) cultivars. Compared to plants fertilized with 10 kg N/ha, plants inoculated with a mixture of Azospirillum sp. (strains Sp 82, Sp 242, and Sp Eng‐501) had increased grain % protein, and leaf % N at 10 DAS and at harvest, but not grain yield. Compared to plants fertilized with either 60 or 180 kg N/ha, Azospirillum‐inoculated plants yielded significantly less, and except for GS activity, which was not influenced by N supply, had lower values for leaf % N at 10 DAS and at harvest, for contents of soluble protein and RUBISCO, and for the activities of PEPC and Fd‐GOGAT. Yield was positively correlated to leaf % N both at 10 DAS and at harvest, to the contents of soluble protein and RUBISCO, and to the activities of PEPC and Fd‐GOGAT, but not of GS, when RUBISCO contents and enzyme activities were calculated per g fresh weight/min. However, when enzyme contents and enzyme activities were expressed per mg soluble protein/min, yield was correlated positively to RUBISCO and PEPC, but negatively to GS. These results give support to the hypothesis that RUBISCO, Fd‐GOGAT, and PEPC may be used as biochemical markers for the development of genotypes with enhanced photosynthetic capacity and yield potential.     

Effects of long‐term applications of various nitrogen sources on chemical soil properties and composition of bromegrass hay

Effects of 15 annual applications (from 1979 to 1993) of ammonium nitrate (AN), urea, ammonium sulfate (AS), and calcium nitrate (CN) applied at 168 and 336 kg N ha^‐1 to bromegrass (Bromus inermis Leyss.) on soil acidification, and concentration of aluminum (Al), iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu) in soil and in hay were investigated in a field experiment on a thin Black Chemozemic (Typic Boroll) soil in Alberta, Canada. Soil was acidified and the concentration of extractable Al, Fe, and Mn was increased by nitrogen (N) application, but the magnitude varied with N source. Soil acidification was greatest with AS, followed by AN and urea, with no effect of CN. At 336 kg N ha^‐1 rate, soil was acidified to a depth of 10, 15 and 30 cm with urea, AN AS, respectively. Soil acidification was also greater at 336 kg than 168 kg N ha^‐1. The CaCl₂‐extractable Al and Fe in the 0–15 cm layer increased with N application, which closely followed the decrease in soil pH from various N sources. Extractable Al and Fe concentration in the 15–30 cm layer increased in response to reduction in soil pH by AS only, and there was no change in the extractable Al and Fe below the 30‐cm depth by any form of N. The DTPA‐extractable Mn in soil generally changed in response to N application. There was no effect of N source on the DTPA‐extractable Zn and Cu in soil. When soil pH had been lowered from N application, the concentration of Al in hay decreased while Zn concentration increased. The Mn concentration in forage increased markedly in response to reduced soil pH from application of AN, urea and AS. There was no effect of N fertilization on the Cu and Fe concentration in hay. In conclusion, the magnitude of soil acidification, changes in the Al, Fe, and Mn concentrations in soil and changes in the Al, Zn, and Mn concentrations in bromegrass hay varied with N source. The results suggest the need for periodic monitoring of soil pH and consideration of liming costs in the economics of various N fertilizers.     

Effect of long-term balanced and imbalanced inorganic fertilizer and FYM application on chemical fraction of DTPA-extractable micronutrients and yields under rice–wheat cropping system in mollisols

The imbalanced use of chemical fertilizers under intensive cultivation practices over a period of years leads to various soil-associated problems particularly nutrient availability. Thus, to examine the effect of long-term application of balanced and imbalanced inorganic fertilizer and farm yard manure (FYM) application on the chemical fraction of DTPA-extractable micronutrients under rice–wheat cropping system after 29 years, the observations were recorded from the ongoing field experiment at Govind Ballabh Pant University of Agriculture and Technology, Pantnagar, India. An application of balanced inorganic fertilizer with FYM in rice, while without FYM in wheat significantly improved the DTPA-extractable Zn, Fe, Mn and Cu after rice and wheat crops in both the surface and sub-surface soil layers. Lowest DTPA-extractable Zn, Fe, Mn and Cu were recorded, in surface and sub-surface soil under rice and wheat crops in control. The highest DTPA-extractable Zn, in both surface and sub-surface layers of rice (3.31, 1.62 mg kg⁻¹, respectively) and wheat (2.96, 0.99 mg kg⁻¹, respectively) was recorded because of application of N₁₈₀+P₈₀+K₄₀+Zn(F) + FYM in rice and N₁₈₀+P₈₀+K₄₀+Zn(F) in wheat. However, the DTPA-extractable Fe, Mn and Cu were highest in rice and wheat because of N₁₂₀+P₄₀+K₄₀+FYM and N₁₂₀+P₄₀+K₄₀ application, respectively. The balanced use of inorganic fertilizer with FYM (N₁₈₀+P₈₀+K₄₀+Zn(F) + FYM) in rice and without FYM [N₁₈₀+P₈₀+K₄₀+Zn(F)] in wheat supported the highest rice (6.74 t ha⁻¹) and wheat (3.50 t ha⁻¹) grain yields, while lowest in control. Based on the study results, long-term application of FYM at 5 tonnes ha⁻¹ in rice crop sustained the availability of DTPA-extractable cationic micronutrients to rice and wheat in Mollisols.     

Nutrient uptake and residual effect of organic treatments applied to vegetable–rice system in an acid soil

Direct and residual effects of organic treatments and in combination with inorganic fertilizers applied to acid soils were studied in the okra–rice system. Among the treatments studied, vermicompost (V.C) and poultry manure improved soil pH and exhibited liming effect, whereas inorganic fertilizer decreased soil pH. Inorganic fertilizer contributed to 78% of net return in okra but the residual effect was observed in inorganic and V.C combination. Soil available nitrogen and potassium had increased at 100% recommended dose, compensated crop uptake at 75%, but depletion was observed at 50%. Uptake of nitrogen was higher for okra from inorganic fertilizer but higher phosphorus and potassium uptake from V.C was observed for rice. Organic treatments showed better correlation between soil pH and zinc (Zn) uptake by okra and significant residual effect on rice. But it reduced the solubility of iron (Fe) and its uptake by okra and indicated a negative correlation between pH and diethylene triamine penta acetic acid-extractable Fe²⁺.     

Cultivation of potato – use of plastic mulch and row covers on soil temperature,growth, nutrient status,and yield

Potato is one of the most important crops in the world because of its high nutritional value; however, traditional cultivation in bare soil may render low yields and poor quality. Crop production efficiency can be increased by using plastic mulching and row covers to modify root zone temperature and plant growth, in addition to reduction in pest damage and enhance production in cultivated plants. However, there is little information demonstrating the effect of row covers in combination with plastic mulch on potato. The aim of this study was to assess the change in root zone temperature and its effect on growth, leaf nutrient, and yield of potato using plastic mulch of different colors, in combination with row covers. Seed of cultivar Mondial was planted in May 2012. The study included four plastic films: black, white/black, silver/black, aluminum/black, and a control with bare soil, which were evaluated alone and in combination with row covers removed at 30 days after sowing in a split-plot design. Higher yields were obtained when no row cover (43.2 t ha^?1) and the white/black film (42.2 t ha^?1) were used. Leaf nitrogen, sulfur, and manganese concentration were higher in plants when row cover was used; in contrast, no–row cover plants were higher in Fe and Zn. Mulched plants were higher in Mn concentration than control plants. There was a quadratic relationship between mean soil temperature and total yield (R² = 0.94), and between plant biomass and total yield (R² = 0.98), between leaf area with total yield (R² = 0.98).     

Effect of conservation agriculture on soil organic and inorganic carbon sequestration and lability: A study from a rice–wheat cropping system on a calcareous soil of the eastern Indo-Gangetic Plains

Increasing soil carbon (C) in arable soils is an important strategy to achieve sustainable yields and mitigate climate change. We investigated changes in soil organic and inorganic carbon (SOC and SIC) under conservation agriculture (CA) in a calcareous soil of the eastern Indo-Gangetic Plains of India. The treatments were as follows: conventional-till rice and wheat (CT-CT), CT rice and zero-till wheat (CT-ZT), ZT direct seeded rice (DSR) and CT wheat (ZT-CT), ZTDSR and ZT wheat without crop residue retention (ZT-ZT), ZT-ZT with residue (ZT-ZT+R), and DSR and wheat both on permanent beds with residue (PB-PB+R). The ZT-ZT+R had the highest total SOC in both 0–15 and 15–30 cm soil layers (20% and 40% higher (p < .05) than CT-CT, respectively), whereas total SIC decreased by 11% and 15% in the respective layers under ZT-ZT+R compared with CT-CT. Non-labile SOC was the largest pool, followed by very labile, labile and less labile SOC. The benefits of ZT and residue retention were greatest for very labile SOC, which showed a significant (p < .05) increase (~50%) under ZT-ZT+R compared with CT-CT. The ZT-ZT+R sequestered ~2 Mg ha⁻¹ total SOC in the 0–15 cm soil layer in 6 years, where CT registered significant losses. Thus, the adoption of CA should be recommended in calcareous soils, for C sequestration, and also as a reclamation technique.     

Influence of poultry manure–derived biochars on nutrients bioavailability and chemical properties of a calcareous soil

This study was conducted to investigate the effects of poultry manure (PM) and its derived biochars on chemical properties of a calcareous soil. PM and biochars prepared at 200°C (B200), 300°C (B300) and 400°C (B400) were applied to a calcareous soil at 2% level (w/w) and incubated for 150 days. Selected soil chemical properties and phosphorous, potassium, iron, manganese, zinc and copper availability and recovery were determined at 1, 15, 45 and 150 days of incubation. Soil nutrients availability, organic carbon (OC), electrical conductivity (EC) and cation exchange capacity (CEC) increased by addition of all organic substances. Biochars prepared at higher temperatures were more effective in increasing soil OC with higher durability compared to other treatments. The addition of PM and B200 decreased soil pH, whereas B400 increased it. Although the highest soil EC was observed in B300- and B400-treated samples in the early stages of incubation, the rate of increase in soil EC was higher for PM- and B200-treated soils compared to other treatments. It was concluded that biochar prepared at 300°C had the highest positive effect on nutrients availability and lasts longer in calcareous soil compared to the other produced biochars and PM.     

Changes in physico-chemical and biological properties of soil under conservation agriculture based pearl millet – mustard cropping system in rainfed semi-arid region

Poor soil health and low soil water content during crop growing period are major factor for low productivity of pearl millet – mustard rotation under rainfed semi-arid regions. The authors evaluated five different tillage and residue management practices for improving physico–chemical and biological properties of soil. Results showed that conservation agriculture (CA) practice (zero tillage (ZT) with 4 t ha^–1 residue retention) exhibited higher proportion of soil macro-aggregate. It also increased infiltration rate of about 15.2% over conventional tillage without residue but ZT increased soil penetration resistance in surface soil layer. In the residue applied plots, ~2–4% (w/w) higher soil water content was maintained throughout the season than the no-residue plots. CA practice had the highest soil organic carbon (4.96 g kg^–1) and microbial biomass carbon (188.3 μg g^–1 soil). Significant and positive correlation was also found between soil organic carbon with infiltration rate (r = 0.73**), mean weight diameter (r = 0.80**) and microbial biomass carbon (r = 0.86**). Thus, this study suggests that ZT with residue retention can be advocated in pearl millet – mustard rotations for improving, productivity, soil health and maintaining higher soil water content in rainfed semi-arid regions.     

Long–term effect of crop rotation and nutrient management on soil–plant nutrient cycling and nutrient budgeting in Indo–Gangetic plains of India

In the present investigation, the long-term effect of pulse crop inclusion in the maize-wheat rotation was assessed for the nutrient availability and soil-plant nutrient cycling under different nutrient management practices. Including pulses in the maize-wheat rotation improved soil organic carbon (SOC) and plant available macronutrients being higher in maize-wheat-mungbean rotation. Inclusion of mungbean to maize-wheat rotation enhanced the nitrogen (33.9%), phosphorus (46.4%), potassium (36.3%), and sulphur (55.5%) uptake in maize crop; likewise, alternate-year chickpea inclusion increased the uptake of these nutrients by 18.2, 19.1, 21.7, 32.1%, respectively. Inorganic fertilization maintained the positive annual balance of nitrogen, phosphorus, and zinc. By contrast, the nutrient balance under organic nutrient management was mostly negative. The magnitude of negative balance of potassium and sulphur was higher in inorganic than that of organic nutrient management. The low nutrient supply (particularly nitrogen) in organic fertilization largely inhibited the yield of cereal crops but not that of pulses. In view of this, the inclusion of pulses in the cereal-cereal systems could cause substantial improvement in soil fertility and sustainability in Indo-Gangetic plains. We infer that supply of nutrients like nitrogen and phosphorus in organic, and potassium and sulphur in recommended inorganic fertilization merit special attention.