A rainfed experiment was conducted at two contrasting rainfall situations of two different states of South India viz., Hyderabad (Telangana) and Tirupathi (Andhra Pradesh) during 2007-08 to standardize the optimum sowing time, plant densities and fertiliser dose for horsegram variety CRIDA 18R released and recommended for cultivation in South India. Results showed that the second fortnight of August and first fortnight of November were suitable optimum times of sowing in Hyderabad and Tirupathi regions respectively due to receipt of rainfall from South West monsoon and North East monsoon at respective locations. Plant densities of 3.33 lakh per hectare with or without 10N + 20P 2 O 5 fertilizer dose yielded higher seed in both the regions. However when the sowing was delayed, wisest decision might be to continue the plant densities of 3.33 lakh population per hectare with or without fertilizer. The results revealed that CRIDA-18R responded to fertilizer up to 10 N +20 P 2 O 5 kg ha -1 with 3.33 lakh plant density but for the varied optimum time of sowing at two different centers with occurrence of favourable rainfall situations, revealing a very flexible sowing time for CRHG-18R in South India.

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Infiltration characteristics of the soil are important to understand the water dynamics in the root zone of a soil-plant system. A laboratory experiment was conducted to study the infiltration characteristics of sandy loam soil under different application rates of super absorbent polymers (SAPs). Four polymer products (P1, P2, P3 and P4) of the commercial value with different concentrations (0.25%, 0.75%, 1.25% and 1.75%) were used and compared with control (soil without polymer). Among four polymer products tested, SAP P3 showed maximum reduction (90%) in the steady state infiltration rate as compared to P1, P2 and P4 tested over different concentrations. The steady infiltration rate was decreased by 3.6 to 1.75, 4.1 to 0.4, 1.4 to 0.52 and 1.6 to 0.76 cm/hr under P1, P2, P3 and P4, respectively in the polymer concentrations of 0.25, 0.75, 1.25 and 1.75%. The infiltration data were fitted to Philip model and model parameters had the best description of the relationship between infiltration rate and application rate of super absorbent polymers in the sandy loam soil with significant reduction in saturated hydraulic conductivity (A) varying from 12.4 to 84.75%. Out of four polymers tested, P3 had more reduction capacity in the infiltration rates of sandy loam soils as compared to other SAPs.

Maize (Zea mays L.) is predominantly grown as a commercial crop in river basins of lower Krishna, Telangana, South India. A long-term crop water balance analysis for maize in two sowing windows (normal sowing: 20 June; late sowing: 25 July) was done for A1b climate change scenario using the downscaled climate data from the GCM model ECHAM5. The crop water balance parameters such as rainfall, effective rainfall, crop evapotranspiration (ET) and irrigation requirements of maize during the two sowing windows were estimated using the CROPWAT model for the base period (1961-90) and long-term period (2011-50; mid-century). In the normal sowing window of maize, there was significant variation in the decadal crop ET (24% to 28%) and irrigation requirements (-7% to 26%) having increasing trend during 2011-2050 over base period. The amount of average decadal rainfall and effective rainfall decreased during 2011-2050 in the range 6% to -23% and 10% to -7% respectively, over the base period. The decadal average rainfall and effective rainfall showed increasing trends of 147-151% and 96-110% respectively, over base period in late sowing window. Also, the crop ET and irrigation requirements exhibited a decreasing trend. The study indicates a shift in the seasonal rainfall in normal sowing window during June to July and it extends up to October and November after the season, indicating more rainfall in late sowing window of maize and scope for rainwater harvesting in the lower Krishna river basin for sustaining maize production.

An integrated farming system (IFS) aims to sustain agricultural production, maintain farm incomes, safeguard the environment and respond to climate change impacts. Experiments in a tribal farmer's fields during 2016–2018 with two IFS models (pulse and cotton) were conducted in the Telangana region, India. An on‐farm reservoir (OFR) is designed for storing surface runoff based on the area and runoff coefficient determined through a modelling approach. The results demonstrated how supplemental irrigation and water harvesting are the most important and proven technologies for improving crop productivity and the efficient use of water in dryland areas of the semi‐arid tropics. The economic analysis indicated that after introduction of OFR technology, farmers' profits were increased under both scenarios of prolonged and short dry spells. According to the results, adoption of the OFR and IFS models not only ensured economic returns but provided regular employment even on less than 1 ha of land, which is usually non‐sustainable if monocropping is being practised. The approaches used in this work might be useful for guiding producers’ decisions in optimizing resources and selecting crops based on economic and water use efficiency. © 2020 John Wiley & Sons, Ltd.

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