G. Ravindra Chary

EFFICIENT TILLAGE AND NUTRIENT PRACTICES FOR SUSTAINABLE PEARL MILLET PRODUCTIVITY IN DIFFERENT SOIL AND AGRO-CLIMATIC CONDITIONS

SUMMARY Long-term field experiments were conducted at Agra, Solapur and Hisar from 2000 to 2008 to identify efficient tillage and nutrient management practices and to develop predictive models that would describe the relationship between crop yields and monthly rainfall for rainfed pearl millet grown on arid and semi-arid Inceptisol, Vertisol and Aridisol soils. Nine treatments comprising a factorial combination of three tillage practices, viz., conventional tillage (CT), low tillage + interculture (LT1) and low tillage + herbicide (LT2) and three fertilizer treatments viz., 100% N from an organic source (F1), 50% organic N + 50% inorganic N (F2) and 100% inorganic N (F3) were tested in a split-plot design at the three locations. Studies revealed that tillage and fertilizer treatments, and their interactions, significantly influenced pearl millet grain yields at the three locations. Prediction models describing the relation between grain yield and monthly rainfall indicated that rainfall occurring in June, July and August at Agra; June and July at Solapur; and June and August at Hisar significantly influenced pearl millet grain yield attained by different treatments. The R 2 values of the model ranged from 0.64 to 0.81 at Agra; 0.63 to 0.92 at Solapur, and 0.75 to 0.89 at Hisar. When averaged over all the treatment combinations, mean pearl millet grain yields varied from 1590 to 1744 kg ha −1 at Agra; 1424 to 1786 kg ha −1 at Solapur; and 1675 to 1766 kg ha −1 at Hisar while their corresponding sustainability yield indice (SYI) varied from 35.4 to 42.2%, 19.9 to 45.6% and 64.1 to 68.3%, respectively. At Agra (Inceptisol), CTF3 resulted in significantly higher mean net returns (Rs 11 439 ha −1 ), benefit-cost ratio (2.33), rainwater use efficiency (RWUE) (3.52 kg ha −1 mm −1 ) and the second best SYI (39.9%). At Solapur (Vertisol), the LT1F3 resulted in significantly higher net returns (Rs 12 818 ha −1 ), benefit-cost ratio (3.52), RWUE (3.89 kg ha −1 mm −1 ) and the fourth best SYI (42.6%). At Hisar (Aridisol), the LT1F3 treatment gave higher net returns (Rs 3866 ha −1 ), benefit-cost ratio (1.26), RWUE (5.05 kg ha −1 mm −1 ) and the fourth best SYI (67.8%). These treatment combinations can be recommended for their respective locations to achieve maximum RWUE, productivity and profitability.

Effect of Soil and Nutrient-Management Treatments on Soil Quality Indices under Cotton-Based Production System in Rainfed Semi-arid Tropical Vertisol

Rainfed semi-arid tropical Vertisols of the Indian subcontinent encounter many problems on account of the physical, chemical, and biological soil qualities and consequently have poor crop yields. To ensure sustainable crop production, there is a need to improve and periodically assess the quality of these soils by adopting suitable soil and nutrient-management practices on a long-term basis. Hence, soil quality assessment studies were conducted at the Central Research Institute for Dryland Agriculture, Hyderabad, India, by adopting an ongoing long-term experiment from Akola Centre (Maharashtra) of All-India Coordinated Research Project for Dryland Agriculture (AICRPDA) for the rainfed Vertisol. This long-term experiment was initiated in 1987 with six soil and nutrient management treatments: T1, control; T2, 50 kg nitrogen (N) + 25 kg phosphorus pentoxide (P2O5) ha−1; T3, 25 kg N ha−1 through leuceana; T4, 25 kg N ha−1 through farmyard manure (FYM); T5, 25 kg N + 25 kg P2O5 + 25 kg N ha−1 through FYM; and T6, 25 kg P2O5 ha−1 + 50 kg N ha−1 through leuceana under cotton + greengram intercropping (1:1). Out of the 19 soil quality parameters studied, significant influence of the soil and nutrient-management treatments was observed on almost all the parameters except exchangeable calcium (Ca), available iron (Fe), labile carbon (LC), and bulk density (BD). A standard methodology using principal component analysis (PCA) and linear scoring technique (LST) was adopted to identify the key indicators and for computation of soil quality indices. The various key soil quality indicators identified for these Vertisols under cotton + green gram system were pH, electrical conductivity (EC), organic carbon (OC), available K, exchangeable magnesium (Mg), dehydrogenase assay (DHA), and microbial biomass carbon (MBC). The soil quality indices as influenced by different long-term soil and nutrient-management treatments varied from 1.46 to 2.10. Among the treatments, the conjunctive use of 25 kg P2O5 ha−1 + 50 kg N ha−1 through leuceana green biomass (T6) maintained significantly higher soil quality index with a value of 2.10 followed by use of 25 kg N + 25 kg P2O5 + 25 kg N ha−1 through FYM (T5) (2.01). The order of percent contribution of these identified indicators to soil quality indices was OC (28%) > MBC (25%) > available K (24%) > EC (7%) > pH (6%) = DHA (6%) > exchangeable Mg (4%). Thus, the findings of the present study could be of immense use to the researchers, land managers, farmers, nongovernment organizations (NGOs) and other stakeholders for making periodical assessment of key indicators of soil quality, identifying the best soil and nutrient-management treatments and practices, and planning for improving soil quality to achieve higher productivity goals on a sustainable basis in rainfed semi-arid tropical Vertisol regions. The methodology of the study could also be useful for other rainfed semi-arid tropical Vertisol regions of the world.

Modeling of Interactive Effects of Rainfall, Evaporation, Soil Temperature, and Soil Fertility for Sustainable Productivity of Sorghum + Cowpea and Cotton + Black Gram Intercrops under Rotation Trials in a Rain-Fed Semi-arid Vertisol

Long-term effects of the different combinations of nutrient-management treatments were studied on crop yields of sorghum + cowpea in rotation with cotton + black gram. The effects of rainfall, soil temperature, and evaporation on the status of soil fertility and productivity of crops were also modeled and evaluated using a multivariate regression technique. The study was conducted on a permanent experimental site of rain-fed semi-arid Vertisol at the All-India Coordinated Research Project on Dryland Agriculture, Kovilpatti Centre, India, during 1995 to 2007 using 13 combinations of nutrient-management treatments. Application of 20 kg nitrogen (N) (urea) + 20 kg N [farmyard manure (FYM)] + 20 kg phosphorus (P) ha−1 gave the greatest mean grain yield (2146 kg ha−1) of sorghum and the fourth greatest mean yield (76 kg ha−1) of cowpea under sorghum + cowpea system. The same treatment maintained the greatest mean yield of cotton (546 kg ha−1) and black gram (236 kg ha−1) under a cotton + cowpea system. When soil fertility was monitored, this treatment maintained the greatest mean soil organic carbon (4.4 g kg−1), available soil P (10.9 kg ha−1), and available soil potassium (K) (411 kg ha−1), and the second greatest level of mean available soil N (135 kg ha−1) after the 13-year study. The treatments differed significantly from each other in influencing soil organic carbon (C); available soil N, P, and K; and yield of crops attained under sorghum + cowpea and cotton + black gram rotations. Soil temperature at different soil depths at 07:20 h and rainfall had a significant influence on the status of soil organic C. Based on the prediction models developed between long-term yield and soil fertility variables, 20 kg N (urea) + 20 kg N (FYM) + 20 kg P ha−1 could be prescribed for sorghum + cowpea, and 20 kg N (urea) + 20 kg N (FYM) could be prescribed for cotton + black gram. These combinations of treatments would provide a sustainable yield in the range of 1681 to 2146 kg ha−1 of sorghum, 74 to 76 kg ha−1 of cowpea, 486 to 546 kg ha−1 of cotton, and 180 to 236 kg ha−1 of black gram over the years. Beside assuring greater yields, these soil and nutrient management options would also help in maintaining maximum soil organic C of 3.8 to 4.4 g kg−1 soil, available N of 126 to 135 kg ha−1, available soil P of 8.9 to 10.9 kg ha−1, and available soil K of 392 to 411 kg ha−1 over the years. These prediction models for crop yields and fertility status can help us to understand the quantitative relationships between crop yields and nutrients status in soil. Because black gram is unsustainable, as an alternative, sorghum + cowpea could be rotated with cotton for attaining maximum productivity, assuring sustainability, and maintaining soil fertility on rain-fed semi-arid Vertisol soils.

Drought Hazards and Mitigation Measures

Droughts are manifestations of significant shortages in all domains of the water cycle. They have adverse impacts on the environment, water availability and water quality, water supply system, hydropower generation, navigation, groundwater balances, vegetation cover, agricultural production, etc. of the affected region. Drought is a regular part of natural cycles and single-most weather related natural disaster affecting livelihoods, developmental activities, natural resources (water, soil, and biodiversity) and economy of a country (http://en.wikipedia.org/wiki/Drought). Although droughts may persist for several years, even a short, intense drought can cause significant damage and severely affect local economy. This global phenomenon has a widespread impact on agriculture. Indeed drought is one of the most serious problems arising from climate variability for human societies and ecosystems (Yurekli and Kurune, 2006). The occurrence of droughts is not limited to a particular region. It has been observed that their impact has been completely different in developed and developing nations because of several socio-economic and political factors influencing both behavioral and management patterns. Even within the developing countries, the effects of droughts can vary significantly, but the fact remains that the economically weaker countries or groups in a country are most severely affected by the droughts.

Statistical Assessment of Sustainability of Finger Millet Yield through Rainfall and Soil Fertility Variables using Regression and Principal Component Models in Rainfed Semi-Arid Alfisol

ABSTRACT Field experiments were conducted in farmyard manure (FYM) and maize-residue (MR) blocks during 1984–2011 with the objective of identifying a superior treatment for attaining maximum finger millet yield and soil fertility at Bangalore. The treatments tested in the FYM block were Control; FYM@10tha−1; FYM@10tha−1 + 50% nitrogen, phosphorus, and potassium (NPK); FYM@10tha−1 + 100%NPK; 100%NPK; and in the MR block, Control; MR@5tha−1; MR@5t ha−1 + 50%NPK; MR@5tha−1 + 100%NPK; 100%NPK. FYM@10t/ha + 100%NPK gave a maximum mean yield of 3207 kg/ha in the FYM block, while MR@5t/ha + 100%NPK gave 2548 kg/ha in the MR block. Regression and principal component (PC) models of yield were developed through soil fertility and rainfall variables to assess the treatments. Maximum yield predictability of 60% and 65% under regression, and 76% and 75% under the PC model were observed for the FYM and MR blocks, respectively. FYM@10t/ha + 50%NPK was superior, with maximum gross returns of Rs.41286/ha and benefit–cost ratio (BCR) of 2.27 in the FYM block compared to MR@5t/ha + 100%NPK (gross returns of Rs.34530/ha and BCR of 2.09) in the MR block with maximum soil fertility, and are recommended for adoption under semi-arid Alfisols.

Evaluation of Pigeonpea (Cajanus cajan L.) based Intercropping Systems under Semi-arid Vertisol in Scarcity Zone of Maharashtra

A field experiment was conducted during kharif for five years (2008 to 2012) at All India Coordinated Research Project for Dryland Agriculture centre, Solapur to evaluate pigeonpea based intercropping systems under Vertisols in scarcity zone of Maharashtra. Among pigeonpea based intercropping systems, pigeonpea + groundnut (1:3) was found superior with mean maximum pigeonpea equivalent yield 1425 kg/ha and mean maximum rainwater use efficiency of 3.19 kg/ha-mm compared to other intercropping systems across five years and also gave mean maximum net returns of 30,307/ha. Further, this intercropping system also recorded relatively higher land equivalent ratio of 1.29 indicating yield advantage of 29% compared to sole crops.

Effects of Soil Management Practices on Key Soil Quality Indicators and Indices in Pearl Millet (Pennisetum americanum (L.) Leeke)–Based System in Hot Semi-arid Inceptisols

Rainfed Inceptisol soils, despite their agricultural potential, pose serious problems, including soil erosion, low fertility, nutrient imbalance, and low soil organic matter, and ultimately lead to poor soil quality. To address these constraints, two long-term experiments were initiated to study conservation agricultural practices, comprising conventional and low tillage as well as conjunctive use of organic and inorganic sources of nutrients in Inceptisol soils of Agra center of the All-India Coordinated Research Project for Dryland Agriculture (AICRPDA). The first experiment included tillage and nutrient-management practices, whereas the second studied only conjunctive nutrient-management practices. Both used pearl millet (Pennisetum americanum (L.) Linn) as test crop. These experiments were adopted for soil quality assessment studies at 4 and 8 years after their completion, respectively, at the Central Research Institute for Dryland Agriculture (CRIDA), Hyderabad, India. Soil quality assessment was done by identifying the key indicators using principal component analysis (PCA), linear scoring technique (LST), soil quality indices (SQI), and relative soil quality indices (RSQI). Results revealed that most of the soil quality parameters were significantly influenced by the management treatments in both the experiments. In experiment 1, soil quality indices varied from 0.86 to 1.08 across the treatments. Tillage as well as the nutrient-management treatments played a significant role in influencing the SQI. Among the tillage practices, low tillage with one interculture + weedicide application resulted in a greater soil quality index (0.98) followed by conventional tillage + one interculture (0.94), which was at par with low tillage + one interculture (0.93). Among the nutrient-management treatments, application of 100% organic sources of nutrients gave the greatest SQI of 1.05, whereas the other two practices of 50% nitrogen (N) (organic) + 50% (inorganic source) (0.92) and 100% N (inorganic source) (0.88) were statistically at par with each other. The various parameters that emerged as key soil quality indicators along with their percentage contributions toward SQI were organic carbon (17%), exchangeable calcium (Ca) (10%), available zinc (Zn) (9%), available copper (Cu) (6%), dehydrogenase assay (6%), microbial biomass carbon (25%) and mean weight diameter of soil aggregates (27%). In experiment 2, SQI varied from 2.33 to 3.47, and 50% urea + 50% farmyard manure (FYM) showed the greatest SQI of 3.47, which was at par with 100% RDF + 25 kg zinc sulfate (ZnSO4) (3.20). Under this set of treatments, the key soil quality indicators and their contributions to SQI were organic carbon (19%), available N (20%), exchangeable Ca (3%), available Zn (4%) and Cu (17%), labile carbon (20%), and mean weight diameter of soil aggregates (17%). The quantitative relationship established in this study between mean pearl millet yields (Y) and RSQI irrespective of the management treatments for both the experiments together could be quite useful to predict the yield quantitatively with respect to a given change in soil quality for these rainfed Inceptisols. The methodology used in this study is not only useful to these Inceptisols but can also be used for varying soil types, climate, and associated conditions elsewhere in the world.

Effect of Organic Manure and Crop Residue Based Long-Term Nutrient Management Systems on Soil Quality Changes under Sole Finger Millet (Eleusine coracana (L.) Gaertn.) and Groundnut (Arachis hypogaea L.) – Finger Millet Rotation in Rainfed Alfisol

ABSTRACT A long-term experiment was conducted to evaluate the effect of integrated use of organic and inorganic sources of nutrients on soil quality and its relation to finger millet yield under two predominant crop rotations viz., groundnut–finger millet and finger millet monocropping in hot moist semiarid rainfed Alfisol soils in South India. Two experiments were laid out separately for each cropping system in a randomized complete block design with five treatments individually with FYM and maize residue-based combinations viz., Control (T1), FYM @ 10t ha −1 or Maize residue (MR) @ 5t ha −1 (T2), farm yard manure (FYM) @ 10t ha −1 or Maize residue (MR) @ 5t ha −1 + 50% RDF (Recommended Fertiliser Dose) N, P2O5 & K2O (T3), FYM @ 10t ha −1 or Maize residue (MR) @ 5t ha −1 + 100% RDF N,P2O5 & K2O (T4), Recommended N, P2O5 & K2O (T5). Thus, four sets of nutrient management systems were evaluated. The results showed that farm yard manure or maize residue application in combination with recommended dose of fertilizer significantly improved the soil physical, chemical, and biological properties compared to control and application of inorganic fertilizers alone. Based on evaluation of 19 soil quality parameters under each of the four nutrient management systems, the common key soil quality indicators emerged out were: organic C (OC), available nitrogen (N), available sulfur (S), and mean weight diameter (MWD) of soil aggregates. A significant correlation between the finger millet yield and the relative soil quality indices (RSQI) indicates the importance of soil quality in these semiarid Alfisol soils. The results and the methodology adopted in the present study could be of importance in improving the soil quality not only for the region of the study, but also in other identical soils and cropping systems across the world.

Effects of Conjunctive Use of Organic and Inorganic Sources of Nutrients on Soil Quality Indicators and Soil Quality Index in Sole Maize, Maize + Soybean, and Sole Soybean Cropping Systems in Hot Semi-arid Tropical Vertisol

The soils in the hot semi-arid tropical (SAT) regions generally have low organic matter and nutrient reserves. Soil-management problems in these soils primarily occur because of poor physical conditions and inadequate drainage through excess runoff, finally resulting in poor crop growth. Hence, the present investigation was conducted to study the long-term impact of conjunctive nutrient use treatments on soil quality indicators and soil quality indices under three cropping systems: (i) sole soybean, (ii) soybean + maize, and (iii) sole maize cropping systems at the Indore Centre of the All-India Coordinated Research Project for Dryland Agriculture (AICRPDA) using Navjot and JS-335 as cultivars of maize and soybean, respectively. In 2005, the soil quality assessment study under this experiment was undertaken after 8 years of experimentation. Soil quality assessment was done by identifying the key indicators using principal component analysis (PCA) and linear scoring technique (LST). Soil quality indices (SQI) and relative soil quality indices (RSQI) were also computed. Results revealed that most of the soil quality parameters were significantly influenced by the conjunctive nutrient management treatments. The common key indicators that emerged in all the treatments were pH, organic carbon (OC), exchangeable magnesium (Mg), available zinc (Zn), copper (Cu), manganese (Mn), and boron (B). The soil quality indices across the management treatments under sole maize system varied from 1.70 to 2.40 and application of 20 kg nitrogen (N) (compost) + 20 kg N through urea as top dressing emerged as a one of the most superior treatments with SQI value of 2.40. The soil quality indices in maize + soybean system varied from 1.12 to 1.47 and application of 20 kg N (compost) + 20 kg N through urea + azotobacter at 2 kg ha−1 proved to be significant with the greatest SQI value of 1.47. In the case of the sole soybean system, the SQI varied from 1.21 to 1.61. After considering all the systems together, the average best performance SQI score (ABP-SQI score) was computed, which varied from 1.14 to 1.56. The greatest value was recorded in the treatment with 20 kg N (compost) + 20 kg N (gliricidia) + 10 kg N (urea). The quantitative relationship developed in this study between mean soybean and maize yields (Y) and RSQI values (X), irrespective of the management treatments, could be quite useful to predict the yield quantitatively with respect to a given change in key indicators for these rainfed Vertisols.

Modeling Effects of Soil Fertility of Nutrients and Precipitation of 22 Years on Sustainable Productivity and Profitability of Pearlmillet and Sorghum Rotation in Semi-arid Vertisols

Based on experiments conducted during 1988–2009 on rainfed pearl millet/sorghum with 9 treatments in Vertisols, an efficient treatment for sustainable productivity is identified. Twenty kg of nitrogen (N) from farmyard manure (FYM) + 20 kg N (urea) + 10 kg phosphorus (P) ha−1 in pearl millet and 40 kg N (urea) + 20 kg P + 25 kg zinc sulfate (ZnSO4) ha−1 in sorghum gave maximum yield and rainwater-use efficiency, whereas 20 kg N (FYM) + 20 kg (urea) + 10 kg P ha−1 in pearl millet and 40 kg (urea) + 20 kg P ha−1 in sorghum and gave maximum soil N, P, and potassium (K) over years. The regression model of 20 kg N (crop residue) + 20 kg N (urea) + 10 kg P ha−1 gave maximum R2 for predicting sorghum equivalent yield separately through precipitation and soil variables, whereas 20 kg N (FYM) + 20 kg N (urea) + 10 kg P ha−1 gave maximum R2 under combined model of both variables. Treatment of 20 kg N (FYM) + 20 kg N (urea) + 10 kg P ha−1 was superior for attaining maximum sorghum equivalent yield of 1062 kg ha−1, net returns of Rs. 4805 ha−1, benefit/cost (BC) ratio of 1.50, and 127 kg ha−1 of soil N, 10.3 kg ha−1 of soil P, and 386 kg ha−1 of soil K over years.