Rainfall during monsoon season and its variability governs the cropping system in the rainfed regions of Raichur. Daily rainfall data of one hundred fourteen years (1913-2020) have been analyzed for establishing the long term averages of monthly, seasonal and annual rainfall and its variability. The overall mean annual rainfall at Raichur region was 672.6 mm with average rainy days of 42 days, and distribution of 486.2 mm, 124.5 mm, 55.9 mm and 6.0 mm in monsoon, post monsoon, summer and winter respectively. The coefficient of variation of 29.8 indicated that rainfall was more or less stable over the years. Monthly rainfall had unimodel peak, September receives maximum mean rainfall of 148.1 mm followed by August (124.8 mm). Within the rainy season, September was the highest rainfall contributing month (22 per cent) followed by August (18.6 per cent). There is an ample scope for rain water harvesting from July to September which can be utilized as crop saving irrigation as well as pre sowing irrigation for succeeding Rabi crops which are generally sown on residual soil moisture. The study also revealed that the rainfall and rainy days during monsoon season ranged from 157.8 to 813.7 mm and 21 to 66 days respectively. According to ‘Nakshatras’, the traditional system of rainfall distribution for agriculture, revealed that the period from Punarvasu to Chitta received good amount of rainfall during which crops like groundnut, sunflower, maize, Bajra and pulses like greengram, pigeon pea and chick pea can be taken up.

The study has been made to analyze the rainfall of six districts of Kalyana Karnataka by utilizing the past 50 years (1971-2020) rainfall data. The rainfall data was critically examined and analyzed statistically for annual and seasonal values followed by computation of trend analysis of annual rainfall. The results revealed that, the highest mean annual rainfall was recorded at Bidar (917.8 mm) followed by Yadgir (877.8 mm) and the lowest at Ballari (559.8 mm). The CV varied between 24.0% (Bidar) to 32.6% (Yadgir). From the skewness analysis it was observed that, skewness varied from 0.3 (Bidar and Koppal) to 0.7 (Yadgir and Raichur). The Yadgir district showed zero Kurtosis and the remaining districts were found to be negatively Kurtosis and it varied from -0.1 to -0.6. The Raichur district showed 0.6 positively Kurtosis. From regression analysis, it was found that, the slopes of regression line of annual rainfall are positive at Bidar, Raichur and Koppal. This shows that these districts have increasing annual rainfall trend. However, since the correlation coefficient value (R2) is too low, the increasing trend is not significant. The remaining stations (Kalaburgi, Yadgir and Ballari) showed negative slope of regression line. This indicates these stations have decreasing trend of annual rainfall. The mean monsoon season rainfall varied between 315.3 mm (Ballari) to 705.8 mm (Bidar) and the CV was found to be more than 30% in all the districts which indicate highly erratic rainfall and the rainfall is not much dependable around the mean rainfall. The skewness analysis revealed that, all the stations showed positive skewness and it varied between 0.3 (Raichur and Koppal) to 0.9 (Yadgir).