Long-term effects of fertilization and manuring on productivity and soil biological properties under rice (Oryza sativa)–wheat (Triticum aestivum) sequence in Mollisols

Long-term effects of chemical fertilizers and farmyard manure (FYM) in rice (Oryza sativa)–wheat (Triticum aestivum) cropping system were monitored for two consecutive years after 38 and 39 years on productivity and soil biological properties of Mollisols. The study encompasses varying chemical fertilizer levels of optimum fertilizer rate (120, 26 and 37 kg ha^?1 N, P and K, respectively) for both the crops. The treatments were application of 50% NPK, 100% NPK, 150% NPK, 100% NPK + hand weeding (HW), 100% NPK + Zn, 100% NP, 100% N, 100% NPK + 15 t FYM ha^?1, 100% NPK(-S) and unfertilized control. The rice and wheat yields were highest with 100% NPK + 15 t FYM ha^?1. This treatment also gave maximum and significantly more counts of bacteria, fungi and actinomycetes in soil than all the other treatments after crop harvest. The soil microbial biomass C (410.0 and 407.5 µg g^?1) and N (44.53 and 48.30 µg g^?1) after rice and wheat, respectively, were highest with 100% NPK + 15 t FYM ha^?1, which were significantly higher over all the other treatments. The activities of soil enzymes like dehydrogenase, acid and alkaline phosphatase, arylsulphatase and urease and CO₂ evolution rate with 100% NPK + 15 t FYM ha^?1 were also found significantly higher over the other treatments. Fertilizer treatments with 100% NPK and 150% NPK were comparable and significantly better than application of 50% NPK, 100% N, 100% NP and 100% NPK(-S) in various studied soil biological properties. Integrated use of 100% NPK with FYM sustained the higher yields and soil biological properties under rice–wheat cropping system in Mollisols. Application of Zn and hand weeding with 100% NPK were found better over 100% NPK alone in rice and wheat productivity. Imbalanced use of chemical fertilizers had the harmful effect on soil biological health.     

Soil Quality for Rice Productivity and Yield Sustainability under Long-term Fertilizer and Manure Application

Productivity and sustainability of rice-rice cropping system depend upon the soil quality which is primarily governed by application of fertilizers and manures. However, such information is limited and hence, the present investigation was carried out in a 9-year-old long-term fertilizer experiment at Bhubaneswar, India. There were seven treatments (control, application of 100% NPK, 150% NPK, 100% NPK + Zn, 100% NPK + FYM, 100% NPK + Zn + B, and 100% NPK + Zn + S) laid out in randomized block design with four replications. Indicators of soil quality (physical, chemical, and biological) were diagnosed from 30 numbers of soil properties measured on the post-wet season soil and soil quality was assessed taking productivity and sustainability of dry season rice as goal functions. Results revealed that the highest productivity and sustainability of dry season rice was found with application of 100% NPK + FYM. This treatment, in general, showed better physical, chemical, and biological properties than rest of the treatments. The highest soil quality index (SQI) was recorded in 100% NPK + FYM (0.941) treatment followed by 150% NPK (0.826) with CEC diagnosed as the only key indicator for rice productivity. For yield sustainability in dry season, reserve K and total N were important contributing 89% and 11%, respectively to the SQI. Therefore, these soil properties could be used to monitor soil quality in wet season. Application of FYM along with 100% NPK could sustain the productivity of dry season rice by improving soil properties under subtropical rice-rice system.     

Effects of 41 Years of Application of Inorganic Fertilizers and Farm Yard Manure on Crop Yields,Soil Quality,and Sustainable Yield Index under a Rice-Wheat Cropping System on Mollisols of North India

The present investigation was carried out to evaluate the effect of integrated nutrient management (INM) on crop yield sustainability and soil quality in a long-term trial initiated during the wet season of 1971 under a humid subtropical climate. Over 41 years of study, 100% nitrogen, phosphorus, and potassium (NPK) + farm yard manure (FYM) at 15 t ha^?1 recorded the most sustainable grain yields. Optimal and superoptimal NPK fertilizers gave quite similar crop yields to that of 100% NPK + FYM at 15 t ha^–1 up to two decades but thereafter yields declined sharply due to emergence of zinc (Zn) deficiency. The sustainable yield index (SYI) values indicated that wheat yields were more sustainable than rice. Soil organic carbon and available N, P, K, and Zn in the control plot decreased the most, whereas 100% NPK + FYM at 15 t ha^–1 improved available N, P and K, maintained soil organic carbon, and decreased Zn over initial levels. Grain yield and SYI were more significantly correlated with Soil Organic Carbon (SOC). Continuous application of FYM contributed the maximum Soil Quality Index (SQI) (0.94), followed by Zn.     

Effect of Integrated Nutrient Management on Soil Fertility and Yield of Rice (Oryza sativa L.) under the System of Rice Intensification in the Indian Subtropics

Field experiments were conducted at Water Management Research Station, Begopara, Nadia, WB, India, during the rabi seasons of 2008–2009 and 2009–2010 to find out the integrated effect of nitrogen (N), phosphorus (P), potassium (K), farmyard manure (FYM) and zinc (Zn) under the system of rice intensification (SRI) techniques using eight treatments on the fertility changes in soil. The results revealed that the amounts of organic carbon and available N content in soil were found to maintain the highest fertility status with the highest yield in T₆ (NPK + FYM 10 tha^?1 + Zn 5 kgha^?1) and gave the highest N uptake (55.98 kgha^?1). The availability of P decreased with the increased level of Zn application and gave the highest P uptake (23.52 kgha^?1) in the treatment T₅ (NPK + FYM 10 tha^?1). The highest Zn content (4.71 mgkg^?1) was recorded in the treatment T₇ (NPK + FYM 10 tha^?1+ Zn 10 kgha^?1).     

Long-Term Effect of Fertilizers and Amendments on Depth-Wise Distribution of Available NPK,Micronutrient Cations,Productivity, and NPK Uptake by Maize-Wheat System in an Acid Alfisol of NorthWestern Himalayas

The present study was undertaken in the ongoing long-term fertilizer experiment initiated during 1972 at experimental farm of Department of Soil Science, Himachal Pradesh Agricultural University, Palampur (India). Soil samples collected from three depths (0–0.15, 0.15–0.30, and 0.30–0.45 m) were analyzed for pH; organic carbon; CEC; available N, P, and K; and micronutrients cations. Continuous use of optimal dose of fertilizers and FYM-influenced pH, organic carbon, CEC, available NPK, and DTPA extractable micronutrient cations significantly. The contents of organic carbon, available N, P, K, Fe, Mn, Zn, and Cu were higher in top soil layer (0–0.15 m) compared to lower depths (0.15–0.30 and 0.30–0.45 m). Highest productivity of wheat (89.89 q ha^?1) and maize (156.52 q ha^?1) was recorded under 100% NPK + FYM, which was at par with 100% NPK + lime. Application of 100% NPK along with amendments (FYM/lime) recorded significantly higher NPK uptake over other treatments.     

Rice-wheat productivity and nutrient status in a lantana- (Lantana spp.) amended soil

Imbalanced and inadequate use of chemical fertilizers is responsible for low rice- (Oryza sativa L.) wheat (Triticum aestivum L.) productivity in many resource-poor farmers' fields. Wheat yields in post-rice soils are also constrained due to soil conditions created by puddling in rice, especially in fine to medium textured soils. Organic amendments are known to improve soil productivity under rice-wheat cropping by way of improving physical conditions and nutrient status of the soil, but their availability is restricted. There is a need to identify locally available and cost-effective organic materials, which have minimal alternate uses as fodder and fuel. We evaluated lantana (Lantana spp. L.) residues, a fast-growing weed in nearby wastelands, as a potential soil organic amendment. Yield trends, and soil and crop nutrient status in a 12-year rice-wheat experiment at Palampur, India, involving four levels (0, 10, 20, and 30 Mg ha^-1 year^-1 fresh mass) of lantana addition were investigated. Chopped lantana was incorporated into soil 10–15 days before puddling. Lantana additions at 10, 20 and 30 Mg ha^-1 increased rice yields on average by 18%, 23% and 30%, wheat yields by 11%, 14% and 20%, and total system productivity (rice + wheat) by 15%, 20% and 26% over controls, respectively, and at the same time saved NPK fertilizer. Linear regression analyses over 12 years did not show any change in yield trends of rice and wheat at P =0.05. Continuous cultivation of rice-wheat significantly increased total C, labile C, and other C indices of soils. Total N, Olsen's P, and NH₄OAc-extractable K in the lantana-amended plots were higher than in the controls. Nutrient concentrations in crop biomass, however, remained generally unaffected by lantana treatments. Results suggest that lantana residues, which improved the nutrient status of soil and system yield, have the potential for resource conservation and sustaining rice-wheat productivity.     

Long-term yield trend and sustainability of rainfed soybean–wheat system through farmyard manure application in a sandy loam soil of the Indian Himalayas

A long-term (30 years) soybean–wheat experiment was conducted at Hawalbagh, Almora, India to study the effects of organic and inorganic sources of nutrients on grain yield trends of rainfed soybean (Glycine max)–wheat (Triticum aestivum) system and nutrient status (soil C, N, P and K) in a sandy loam soil (Typic Haplaquept). The unfertilized plot supported 0.56 Mg ha⁻¹ of soybean yield and 0.71 Mg ha⁻¹ of wheat yield (average yield of 30 years). Soybean responded to inorganic NPK application and the yield increased significantly to 0.87 Mg ha⁻¹ with NPK. Maximum yields of soybean (2.84 Mg ha⁻¹) and residual wheat (1.88 Mg ha⁻¹) were obtained in the plots under NPK + farmyard manure (FYM) treatment, which were significantly higher than yields observed under other treatments. Soybean yields in the plots under the unfertilized and the inorganic fertilizer treatments decreased with time, whereas yields increased significantly in the plots under N + FYM and NPK + FYM treatments. At the end of 30 years, total soil organic C (SOC) and total N concentrations increased in all the treatments. Soils under NPK + FYM-treated plots contained higher SOC and total N by 89 and 58% in the 0–45 cm soil layer, respectively, over that of the initial status. Hence, the decline in yields might be due to decline in available P and K status of soil. Combined use of NPK and FYM increased SOC, oxidizable SOC, total N, total P, Olsen P, and ammonium acetate exchangeable K by 37.8, 42.0, 20.8, 30.2, 25.0, and 52.7%, respectively, at 0–45 cm soil layer compared to application of NPK through inorganic fertilizers. However, the soil profiles under all the treatments had a net loss of nonexchangeable K, ranging from 172 kg ha⁻¹ under treatment NK to a maximum of 960 kg ha⁻¹ under NPK + FYM after 30 years of cropping. Depletion of available P and K might have contributed to the soybean yield decline in treatments where manure was not applied. The study also showed that although the combined NPK and FYM application sustained long-term productivity of the soybean–wheat system, increased K input is required to maintain soil nonexchangeable K level.     

Micronutrients (Fe,Mn, Zn and Cu) balance under long-term application of fertilizer and manure in a tropical rice-rice system

Purpose

The balance of micronutrients in soils is important in nutrient use efficiency, environmental protection and the sustainability of agro-ecological systems. The deficiency or excess of micronutrients in the plough layer may decrease crop yield and/or quality. Therefore, it is essential to maintain appropriate levels of micronutrients in soil, not only for satisfying plant needs in order to sustain agricultural production but also for preventing any potential build-up of certain nutrients.

Materials and methods

A long-term fertilizer experiment started in 1969 at Central Rice Research Institute, Cuttack, Odisha, India. Using this experiment, a study was conducted to analyze the balance of micronutrients and their interrelationship. The experiment was composed of ten nutrient management treatments viz. control; nitrogen (N); N + phosphorus (NP); N + potassium (NK); nitrogen, phosphorus and potassium (NPK); farmyard manure (FYM); N + FYM; NP + FYM; NK + FYM; and NPK + FYM with three replications. Micronutrients in soil (total and available), added fertilizers and organic manures and in rice plant were analyzed. Besides, atmospheric deposition of the micronutrients to the experimental site was also calculated. A micronutrient balance sheet was prepared by the difference between output and input of total micronutrients.

Results and discussion

Application of FYM alone or in combination with chemical fertilizer increased the diethylenetriamine pentaacetate (DTPA)-extractable Fe, Mn and Zn over the control treatment. The treatment with NPK + FYM had the highest soil DTPA-extractable Fe, Mn, Zn and Cu after 41 years of cropping and fertilization. Application of chemical fertilizers without P decreased the DTPA-extractable Zn over the control while the inclusion of P in the fertilizer treatments maintained it on a par with the control. The application of P fertilizer and FYM either alone or in combination significantly increased the contents of total Fe, Mn, Zn and Cu in soil mainly due to their micronutrient content and atmospheric depositions. A negative balance of Zn was observed in the N, NP, NK and NPK treatments, while a positive balance observed in the remaining treatments. The balance of Mn was negative in all the treatments, due to higher uptake by the rice crop than its addition.

Conclusions

Long-term application of chemical fertilizers together with FYM maintained the availability of micronutrients in soil and, thus, their uptake by rice crop.

     

Influence of mineral and organic fertilizers on soil organic carbon pools

Abstract

The influence of farmyard manure (FYM) and equivalent mineral NPK application on organic matter content, hot water extractable carbon (HWC), microbial biomass C (C_mic), and grain yields in a long-term field experiment was assessed after 40 years in Hungary. The unfertilized plot, FYM fertilized plots and plots fertilized with equivalent NPK fertilizer contained 0.99%, 1.13% and 1.05% total organic carbon (TOC) respectively. Compared to the unfertilized plot, FYM application resulted in 8.2% higher TOC than equivalent NPK fertilization. The highest TOC was only 1.21%, much lower than expected for a soil containing 21.3% of clay. The quantity of HWC varied depending on the type of fertilization: Compared to control, FYM treatments lead to 29% more HWC than mineral fertilization (FYM: 328 mg kg^?1; NPK: 264 mg kg^?1). The impact of FYM and equivalent NPK fertilizer on C_mic was contrary. FYM and NPK resulted in 304 and 423 mg kg^?1 C_mic, respectively. The difference was 119 mg kg^?1; 42% as compared to the unfertilized plot. Despite the higher HWC content, FYM treatments lead to significantly less (35%) grain yields than equivalent NPK doses; C_mic content showed closer correlation to grain yields.     

Long‐term effects of fertilizer and manure applications on soil quality and yields in a sub‐humid tropical rice‐rice system

Widespread yield stagnation and productivity declines in the rice–rice cropping system have been reported and many of the associated issues are related to soil quality. A long‐term experimental study was initiated in 1969 to assess the impact of continuous cultivation of rice as a single crop grown in wet as well as dry seasons using varying levels of chemical fertilizer and manure applications on soil quality indicators (physical, chemical and biological), a sustainable yield index (SYI) and a soil quality index (SQI). The treatments comprised chemical fertilizers and farmyard manure (FYM) either alone or in combination viz. control, N, NP, NK, NPK, FYM, N+FYM, NP+FYM, NK+FYM and NPK+FYM, laid out in a randomized complete block design with three replications. Soil samples were collected after the wet season rice harvest in 2010 and were analysed for physical, chemical and biological indicators of soil quality. A SYI based on long‐term yield data and SQI using principal component analysis (PCA) and nonlinear scoring functions were calculated. Application of NPK fertilizers in combination with FYM significantly increased the average grain yield of rice in both wet and dry seasons and enhanced the sustainability of the system compared to the control and plots in receipt of fertilizers. The SYI for the control was higher in the wet season than in the dry one, whereas the reverse was true for NPK+FYM treatment. The value of the dimensionless SQI varied from 1.46 in the control plot to 3.78 in the NPK+FYM one. A greater SYI and SQI in the NPK+FYM treatment demonstrated the importance of using a chemical fertilizer in combination with FYM. For the six soil quality indicators selected as a minimum data set (MDS), the contribution of DTPA‐Zn, available‐N and soil organic carbon to the SQI was substantial ranging from 59.4 to 85.7 per cent in NPK+FYM and control plots, respectively. Thus, these soil parameters could be used to monitor soil quality in a subhumid tropical rice–rice system.     

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.     

Long-Term Organic Amendment Application Improves Influence on Soil Aggregation,Aggregate Associated Carbon and Carbon Pools under Scented Rice-Potato-Onion Cropping System after the 9th Crop Cycle

A field experiment was conducted to investigate the influence of long-term application of organic manures on aggregate stability, associated carbon concentrations and carbon pools as an important soil-quality parameter under a scented rice-potato-onion cropping system in silt-loam textured soil in Eastern Bihar, India (subtropical climatic condition). Five treatments were used: 1) nitrogen, phosphorus and potassium (NPK) – 100% recommended dose of NPK; 2) NPK+FYM (farmyard manure) – 50%NPK+50% N as FYM; 3) FYM+VC (vermicompost)+ NC (neem cake) – different organic sources each equivalent to 1/3 of the recommended N (FYM +VC +NC); 4) FYM+VC+NC+PSB (phosphate-solubilizing bacteria – different organic sources each equivalent to 1/3 of the recommended N (FYM +VC+NC)+biofertilizers containing N and P carriers (PSB) and 5) FYM+BFN+BM+PSB – 50% N as FYM + biofertilizer for N +Bone meal to substitute P requirement of crops + PSB. The aggregate size distribution (>250 μm) at different soil depths is higher in treatment FYM+VC+NC+PSB and is at par with FYM+VC+NC, followed by FYM+BFN+BM+PSB and NPK+FYM, and the lowest in treatment receiving 100% NPK. The mean carbon concentration in each soil fraction was higher in soil depth 0–10 cm, followed by 10–20 cm and 20–30 cm. The trend of mean weight diameter (MWD) in different treatments was FYM+VC+NC+PSB ≥ FYM+VC+NC > NPK+FYM > FYM+BFN+BM+PSB > NPK. The trend of carbon concentrations in different treatments was FYM+VC+NC+PSB ≥ FYM+VC+NC > FYM+BFN+BM+PSB ≥ NPK+FYM > NPK. Non-labile pool of carbon forms the major portion (60.14%) of the total soil organic carbon (SOC) irrespective of all depths. Bulk density (BD) has a significant role in stabilizing soil aggregates as well as increasing the SOC content in soil. SOC was negatively correlated with BD (r = ?0.870, p = 0.05), MWD (r = ?0.911, p = 0.01) and geometric mean diameter (GMD) (r = ?0.958, p = 0.05) irrespective of depth. This study took further steps toward understanding the enhancing of aggregate stability on organic manures addition for soil quality improvement.     

Effect of Mycorrhiza,Organic Sources,Lime, Secondary and Micro-nutrients on Soil Microbial Activities and Yield Performance of Yam Bean (Pachyrhizus erosus L.) in Alfisols

Effect of integrated use of mycorrhiza, lime, inorganic fertilizers, and organic manures on microbial activities and yield performance of yam bean (Pachyrhizus erosus L.) was studied for two consecutive kharif (rainy) seasons during 2013–14 and 2014–15 in an acid Alfisol. The experiment was laid out with 16 treatments consisting of graded doses of soil test–based nitrogen, phosphors, and potassium (NPK); lime; mycorrhiza; organic sources, that is, farmyard manure (FYM), vermicompost, and green manure; secondary magnesium sulfate (MgSO₄) and micronutrients zinc sulfate (ZnSO₄ and borax). Significantly highest mean tuber yield (29.61 t ha^?1) was recorded due to integrated application of lime + FYM + NPK + ZnSO₄. Graded doses of NPK showed a mean yield response of 65%, 134%, and 191% due to addition of 50%, 100%, and 150% of NPK over control, respectively. Inoculation of vesicular–arbuscular mycorrhiza (VAM) combined with NPK and FYM recorded a mean tuber yield of 25.14 t ha^?1. Highest mean dry matter (18.85%) was recorded due to application of 150% NPK, whereas highest starch content on fresh weight basis was recorded due to integrated use of lime + FYM + NPK + MgSO₄ (11.11%). Application of 150% NPK has recorded highest dehydrogenase activity (2.018 µg TPF h^?1 g^?1) and fluorescein diacetate hydrolysis assay (2.012 µg g^?1 h^?1). Fungal inoculation of VAM in combination with lime + FYM + NPK recorded highest acid and alkaline phosphatase activities (82.20 and 67.02 µg PNP g^?1 soil h^?1, respectively). Soil biological activities and phosphatase activities had highly significant relationship with tuber yield and biochemical constituents of yam bean. The study emphasized the conjunctive use of soil test–based inorganic fertilizers, lime, and organic manures to enhance the enzymatic activities and to realize higher crop yields of yam bean in acid Alfisols.     

猪粪沼液施用对稻、麦产量和氮磷吸收的影响

在江苏太湖稻麦轮作区,开展了连续2年不同沼液替代化肥比例及沼液基追比的等氮田间试验,结果表明:单施化肥处理(NPK)及沼液化肥配施处理水稻、小麦生物量及产量均显著高于无肥对照,各处理以75％沼液替代比例分3次施入(N75％)处理的水稻生物量和产量为最高,其生物量及产量分别比单施化肥处理提高2.7％和7.5％;而小麦生物量和产量以50％沼液替代比例(N50％)处理最高,其生物量和产量比单施化肥处理分别提高15.9％和7.8％.沼液化肥配施对稻麦的增产作用主要体现在提高水稻与小麦总穗数及穗粒数上;各处理水稻、小麦的氮素累积量和氮素当季表观利用率分别以75％(N75％)和50％(N50％)替代比例为最高;在50％～ 100％替代比例内沼液分次施用,水稻、小麦氮肥农学效率、偏生产力都高于化肥处理.水稻、小麦不同器官的氮分配比例显示,沼液配施化肥促进氮素向籽粒转移;相同沼液替代比例下,沼液分次施用水稻、小麦的产量、氮素累积量及氮素利用率均较基肥一次性施入高.稻、麦根、叶部磷含量分别以N75％和N100％处理最高.以上表明稻麦配施50％ ～ 75％的沼液分3次施用,可获得与纯化肥处理相当的产量,且在一定程度上提高稻麦氮素利用率.     

Soil carbon pools under long-term rice-wheat cropping system in Inceptisols of Indian Himalayas

Knowledge about soil organic carbon (SOC) stock and its allocation into different pools is important for global food and environmental security. Accordingly, an attempt is made in the present study to investigate into the dynamics of SOC pools i.e. total soil organic carbon (TOC), oxidisable organic carbon (OC) and its different fractions viz. very labile (C_VL), labile (C_L), less labile (C_LL) and non-labile (C_NL) in soils under a 26 years old long-term experiment with rice (Oryza sativa L) – wheat (Triticum aestivum L) cropping system on Inceptisols under humid agro-climatic region of India with different soil management practices (control, 100% recommended dose of NPK, and 50% recommended dose of NPK + 50% N through farmyard manure (FYM). Of the several pools analyzed, a higher proportion of C was found in labile pool followed by very labile, non-labile, and less labile ones constituting about 46, 26.5, 20 and 7.3% of the total organic C at surface soil. The NPK+FYM treatment was found to have higher SOC pools, lability index (LI), recalcitrance indices and stratification ratio as compared to others. Results indicated that balanced fertilization with inorganic and organics is important for maintaining overall sustainability of the rice-wheat system.     

Water Use and Soil Fertility under Rice–Wheat Cropping System in Response to Green Manuring and Zinc Nutrition

ABSTRACT

Soil fertility and water use are two important aspects that influence rice productivity. This study was conducted to evaluate the performance of in-situ (sesbania and rice bean) and ex-situ (subabul) green manuring along with zinc fertilization on water productivity and soil fertility in rice under rice–wheat cropping system at Indian Agricultural Research Institute, New Delhi, India. Sesbania incorporation recorded higher total water productivity (2.20 and 3.24 kg ha^?1 mm^?1), available soil nutrients, organic carbon, alkaline phosphatase activity, microbial biomass carbon and increased soil dehydrogenase activity by 39.6 and 26.8% over subabul and rice bean respectively. Among interaction of green manures and zinc fertilization, subabul × foliar application of chelated zinc-ethylenediaminetetraacetic acid at 20, 40, 60 and 80 days after transplanting recorded highest total water productivity (2.56 and 3.79 kg ha^?1 mm^?1). Foliar application of chelated Zn-EDTA at 20, 40, 60 and 80 days after transplanting recorded significantly higher water productivity than other Zn treatments, however it was statistically similar with foliar application of zinc at active tillering + flowering + grain filling. Sesbania × 5 kg Zn ha^?1 through chelated Zn-EDTA, recorded highest available nitrogen, phosphorus, potassium, zinc, manganese, copper and iron than other green manure and Zn fertilization interactions, although it was statistically similar with rice bean × 5 kg Zn ha^?1 through chelated Zn-EDTA as soil application. Sesbania × foliar application of 5 kg Zn ha^?1 through chelated Zn-EDTA as soil application recorded highest soil enzymatic activities and microbial biomass carbon.     

Changes in the soil properties and availability of micronutrients after six-year application of organic and chemical fertilizers using STCR-based targeted yield equations under pearl millet-wheat cropping system

Field experiments were carried out to assess the effect of nutrient management on soil properties and available micronutrients using Soil Test Crop Response (STCR) based targeted yield equations under a six-year old pearl millet-wheat cropping system. After six years, results showed that soil pH and bulk density decreased, while cation exchange capacity and organic carbon increased in farmyard manure (FYM) as compared to control and nitrogen, phosphorus and potassium (NPK) treated plots in both surface and sub-surface soil depths. Higher values of available zinc (Zn) (1.54 mg kg^?1) and iron (Fe) (5.68 mg kg^?1) were maintained in FYM+NPK treated plots, while higher values of manganese (Mn) (6.16 mg kg^?1) and copper (Cu) (1.07 mg kg^?1) were found in FYM alone at surface soil as compared to sub-surface soil. This study demonstrated the importance of application of FYM in improving soil properties and maintaining micronutrients availability in soil and their uptake by wheat for sustainable crop production.     

Dynamics of zinc under long-term application of chemical fertilizers and amendments by maize–wheat cropping sequence in Typic Hapludalfs

This present investigation took place on a continuing long-term fertilizer experiment, initiated in 1972 at the experimental farm of the College of Agriculture CSK HPKV, Palampur, aimed at studying nutrient dynamics of micronutrients, especially Zn, after continuous use of chemical fertilizers and amendments over the previous 36 years in an acid Alfisol under a maize–wheat system. Treatments investigated were as follows: T₁: Control; 100% N; 100% NP; 100% NPK (optimal application - 120:26:33(maize)/25(wheat)); 100% NPK + FYM (10 t ha⁻¹ to the maize crop); T₆: 100% NPK + lime (900 kg ha⁻¹); T₇: 100% NPK + Zn (25 kg ha⁻¹ as ZnSO₄); T₈: 100% NPK + Hand weeding; T₉: 100% NPK (-S); T₁₀: 150% NPK (super-optimal application); and T₁₁: 50% NPK (sub-optimal application). Different forms of zinc in soil were determined through a sequential extraction method. Results revealed that previous applications of high-analysis fertilizers and amendments caused a marked depletion in the pools of Zn as compared to buffer plots. All pools of Zn as well as crop productivity and Zn uptake were noticeably greater in farmyard manure (FYM)-amended plots compared with plots not receiving fertilizer. The residual fraction was the dominant form but organically bound and exchangeable forms were found to play major role in nutrient supply, crop productivity and nutrient uptake. Correlation and regression analysis studies showed that organic forms constituted the most important pool contributing towards variation in yield and uptake by maize and wheat crops. Exchangeable and organically bound forms contributed significantly towards the availability of DTPA-extractable Zn in soil.     

Manure and Fertilizer Application Effects on Aggregate and Mineral-Associated Organic Carbon in a Loamy Soil under Rice-Wheat System

The study was conducted to investigate the aggregate stability and distribution of organic carbon (C) in different-sized aggregates and mineral fractions in a loamy soil under rice-wheat system with continuous application of fertilizer nitrogen, phosphorus and potassium (NPK), farmyard manure (FYM), N+FYM and NPK+FYM, compared with unfertilized control. Macro-aggregates comprised 37.1–49.3% of the total water-stable aggregates (WSAs), compared with 23.3–30.3% as micro-aggregates. Application of inorganic fertilizers and FYM significantly increased the proportion of macro-aggregates, which were linearly related to total organic C (TOC). Organic C concentration in coarse macro-aggregates (CMacA) was higher than the micro-aggregates (CMicA). Application of FYM significantly increased the concentration of organic C in different-sized aggregates and mineral fraction, compared with the unfertilized control. Averaged across treatments, mineral-associated C comprised 26% of TOC. Macro-aggregates, on an average, constituted 66–68% of C preservation capacity of WSA. The amount of TOC sequestered was higher when NPK+FYM was applied together.     

缓释氮肥运筹对稻麦轮作周年作物产量和氮肥利用率的影响

【目的】稻麦轮作是我国一种重要的农业种植模式。缓/控释肥作为高效兼环境友好的肥料类型,在多种作物单季种植上具有增产和提高肥效的作用,但是缓释肥在周年轮作体系中的肥效研究鲜有报道。因此研究稻麦轮作体系中的肥料施用模式,有助于提高稻麦产量,降低化肥用量,提高化肥利用率。【方法】本文通过稻麦轮作两周年四季作物的田间小区试验,以不施氮和习惯施氮为对照,研究了4种不同缓释肥减氮处理[进口树脂包膜尿素减氮24.3%、 国产硫包衣尿素减氮24.3%、 国产尿素加NAM(长效氮肥添加剂)减氮24.3%和国产尿素加NAM减氮10.8%]对水稻和小麦产量、 氮肥利用率、 第二周年稻麦收获后土壤养分含量和两周年土壤氮养分表观平衡的影响。【结果】与不施氮对照相比,所有施氮处理均提高了两周年稻麦4季作物产量,习惯施氮增产幅度最高,小麦的氮肥增产效果总体高于水稻,第二周年高于第一周年; 与当地习惯施氮量相比,所有的缓释氮肥减氮24.3%或10.8%处理均无显著降低两季小麦产量,进口树脂包膜尿素减氮24.3%处理和国产尿素加NAM减氮10.8%处理也无显著降低两季水稻产量,但是国产尿素加NAM减氮24.3%处理显著降低了第二季水稻产量,国产硫包衣尿素减氮24.3%显著降低了两季水稻产量; 与当地习惯施氮量相比,4个缓释氮肥减氮处理均提高了第一和第二周年氮肥利用率,显著降低了两周年稻田土壤养分氮盈余量,其中国产尿素加NAM减氮24.3%处理氮肥利用率较高,同时土壤氮盈余量较少,说明缓释氮肥减量在提高肥料利用率和降低氮的环境效应上具有一致的优势; 不同缓释氮肥对土壤养分含量的影响无明显规律性。【结论】在目前稻麦轮作体系中,缓释氮肥减施对小麦产量具有较好的稳定效果,但是个别缓释氮肥减施对水稻有减产风险,有必要依据稻田土壤氮素转化特点,研制水稻专用缓释氮肥,适当降低水稻季缓释氮肥的施用量。