SOIL TEST CROP RESPONSE CORRELATION STUDIES IN INDIAN MUSTARD (Brassica juncea L.)

A field experiment was conducted on soil test crop response correlation studies in Indian mustard in sequence to the fertility gradient trial at the students’ farm, College of Agriculture, Rajendranagar, Hyderabad. The soil was sandy loam in texture, neutral in reaction with 7.1 pH, and normal in electrical conductivity (ECe) with 0.138 dS/m. The nutrient status was low in available nitrogen (213.3 kg N / ha), high in phosphorus (70.0 kg P2O5 /ha) and medium in potassium (269.0 kg K2O/ ha). The fertility gradient experiment was conducted by growing fodder sorghum variety SSG 59-3 on 30.06. 05 during Kharif 2005. The results showed a wide variability in the soil nutrient available status between the strips after the harvest of the crop. This variation was best reflected in the grain yield of 1.51, 6.19 and 9.14 q / ha recorded in 0 X, 1 X and 2 X fertility gradients. The fodder yield was 31.83, 84.21 and 82.78 q / ha in the corresponding gradients. In the subsequent rabi season mustard variety Pusa Jaikisan was sown on 25.11. 05 for soil test crop response correlation studies. A total number of 24 treatments involving 21 combination levels of NPK through fertilizers and three controls were executed in each of the three fertility gradients. The results showed that the vegetative crop growth characteristics viz; plant height, number of branches and leaves per plant, dry matter of leaves, stem and the yield components viz; number of siliquae per plant, their dry weight, number of seed per siliqua, test weight and seed yield per plant improved substantially by growing the crop in 1 X and 2 X than in the 0 X fertility gradients. The application of NPK through fertilizers to mustard further improved these parameters compared to control and this improvement was more prominent in the 1 X and 2 X than in the 0X fertility gradients. The removal of NPK through the leaves, stem, siliquae, seed and the entire plant was more in the 1 X and 2 X than the 0 X fertility gradient. The application of fertilizers further improved this trend. The oil content increased by the application of 40 kg N/ha and decreased with further increase up to 120 kg N/ha. Application of 20 kg P2O5/ha also increased the oil per cent. Oil yield increased by the application of fertilizers up to 80 kg N, 60 kg P2O5 and 40 kg K2O / ha. Mustard produced 5.4 q/ha seed yield by the application of 120 kg N / ha in the 0 X fertility gradient but 80 kg N / ha was sufficient to harvest 6.3 and 5.4 q / ha seed yield in the 1 X and 2 X fertility gradients. Stover yield increased to maximum by the application 120 kg N / ha. The crop produce maximum seed yield of 4.5 q/ha by the application of 60 kg P2O5 / ha in the 0 X fertility gradient. It required only 20 kg P2O5 / ha and yet produced more seed yield of 5.7 q/ha in the 1 X and 2 X fertility gradients. Maximum stover yield was obtained by the application of 60 kg P2O5 / ha. The crop required 60 kg K2O / ha to produce 5.4 q seed yield in the 0 X fertility gradient. But, it produced 6.5 and 5.2 q / ha seed yield by the application of only 20 kg K2O / ha in the 1 X and 2 X fertility gradient. Maximum stover yield was obtained by the application of 60 kg K2O / ha. Significant correlation coefficients were established between the NPK applied through fertilizers and seed yield. The multiple linear regression explaining the contribution of NPK through soil, fertilizer and interaction was Y = 703.001 + 10.8180 FN – 0.0343 FN – 0.6990 SN + 0.0004 SN – 0.0070 FNSN – 11.575010 FP – 0.0267 FP + 2.7210 SP + 0.0610 SP + 0.1760 FPSP + 10.0180 FK – 0.0907 FK – 4.7030 SK 0.0047 SK – 0.0071 FKSK . R = 0.49 The + response for linear, quadratic and interaction term was obtained from N and K. Therefore, a ready reckoner of N and K to be applied for soils with different levels of these nutrients to obtain maximum yield, maximum profit and desired rate of return were developed from the fertilizer adjustment equations F N = 157.70 – 0.1025 SN – 14.58 R F K2O = 55.23 – 0.0392 SK – 5.52 R The targeted yield equations developed from the basic parameters were F N = 27.50 T – 0.12 SN F P2O5 = 10.25 T – 0.19 SP F K2O = 9.02 T – 0.03 SK A ready reckoner was developed for targeted yield goals of 6 and 10 q/ha seed yield of mustard. The nutrient budgeting recorded higher balance of nitrogen in 0 X and 1 X fertility gradient than the initial value. Phosphorus was build up to more than the initial soil test value in the three gradients. The actual balance of potassium was also more than the initial soil test value in the 0 X and 1 X gradients while it was low in the 2 X fertility gradient.