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ThesisItem Open Access Long-term effects of fertilizers and organic manures on yield and dynamics of phosphorus and potassium in soil under pearl millet-wheat cropping sequence(CCSHAU, 2016) Binjola, Sonam; Antil, R.S.An ongoing long-term field experiment on integrated nutrient management under pearl millet-wheat cropping sequence initiated in 1995 at the Soil Science Research Farm of CCS Haryana Agricultural University was selected for this study. The experimental treatments consisted of T1: 75 kg N + 30 kg P2O5 ha -1 , T2: 150 kg N + 60 kg P2O5 ha -1 , T3: 15 Mg FYM ha -1 , T4: 15 Mg FYM + 150 kg N ha -1 + 30 kg P2O5 ha -1 , T5: 5 Mg poultry manure ha -1 , T6: 5 Mg poultry manure + 150 kg N ha -1 + 30 kg P2O5 ha -1 , T7: 7.5 Mg pressmud ha -1 , T8: 7.5 Mg pressmud ha -1 + 150 kg N ha -1 + 30 kg P2O5 ha -1 The experiment was laid out in a randomized block design with three replications. Grain yield of wheat was significantly affected by integrated use of fertilizers and organic manures after 19 cycles of pearl millet-wheat cropping sequence. Pressmud with NP fertilizers recorded the highest wheat grain yield (68.3 q ha -1 ) followed by FYM with NP fertilizers and lowest with poultry manure applied in combination with NP fertilizers. There was an increase of about 122, 141 and 90 % in wheat grain yield upon application of 15 t FYM, 5 t poultry manure and 7.5 t pressmud ha -1 along with recommended N and half of P over manures applied alone, respectively. Application of pressmud along with fertilizers enhanced total N and P uptake to the tune of 301.1 kg ha -1 and 68.7 kg ha -1 whereas, total K uptake was highest (191.9 kg ha -1 ) under the treatment with FYM plus fertilizers. Long-term effect of fertilizers and organic manures on periodical changes of various inorganic P and K fractions at different days of wheat growth tended to decline with the crop age. Highest increase both in hydraulic conductivity and infiltration rate were noticed when organic manures were applied in combination with NP fertilizers. Bulk density was found to be invariant with respect to different treatments. The changes in soil inorganic P fractions (Al-P, Ca-P, Fe-P and saloid bound-P) and inorganic K fractions (water soluble- K, exchangeable- K and non exchangeable- K) were more dynamic under the treatments consisted of organic manures in combination with fertilizers. Amongst the different treatments, highest inorganic P fractions were observed under the treatment consisted of pressmud in combination with NP fertilizers followed by the treatment consisted of poultry manure in combination with NP fertilizers and the treatment consisted of FYM in combination with NP fertilizers. The effect of FYM in conjunction with NP fertilizers was found to be more pronounced in increasing all the inorganic K fractions. Both soil organic carbon and available K increased significantly by the long-term application of organic manures plus NP fertilizers and were recorded highest with application of FYM and NP fertilizers. Available P content varied from 12.4 to 38.8 mg kg -1 and was observed highest with combined application of pressmud and NP fertilizers. A decrease in soil pH was observed under organic manures treatment along with fertilizers whereas, electrical conductivity of soil was increased with the application of organic manures alone or with fertilizers. The build-up of P fractions (Fe-P and saloid bound-P), K fractions, infiltration rate, hydraulic conductivity, organic carbon, available P and K and soil pH were higher in surface (0-15 cm) soil as compared to sub-surface (15-30 cm) soil. However, the reverse trend was followed in case of P fractions (Al-P and Ca-P) and bulk density. This study also corroborates the results of an another long-term experiment running since 1985 and showed the residual effect of treatments added during kharif which have been supplied with recommended doses of fertilizers during rabi using different organic manures (FYM, green manure and wheat straw) along with fertilizers in kharif treatments under pearl millet-wheat cropping system. The experiment consisted of seven treatments- T1: control, T2: 50 % recommended NPK dose through fertilizers, T3: 100 % recommended NPK dose through fertilizers, T4: 50 % recommended NPK dose through fertilizers + 50 % N through FYM, T5: 50 % recommended NPK dose through fertilizers + 50 % N through wheat straw, T6: 50 % recommended NPK dose through fertilizers + 50 % N through green manure, T7: Farmer’s practice. The experiment was laid out in a randomized block design with three replications. Application of 50 % N through FYM along with 50 % recommended NPK fertilizers led to the greatest increase in yield of wheat and total NPK followed by the 50 % N through green manure along with 50 % recommended NPK fertilizers treatment plus 100 % recommended dose of fertilizers treatment. There was an increase of about 415, 433, 400 and 420 % in wheat grain yield on 100% RDF, FYM amended, wheat straw amended and green manure amended plot over control, respectively. Application of organic manures along with NPK fertilizers plus 100 % RDF treatment resulted in higher build up of inorganic P and K fractions. The highest value of inorganic P fractions was maintained under FYM plus NPK treatment followed by only 100 % NPK treatment. Treatment with pressmud plus NPK recorded highest soil inorganic K fractions as compared to the other treatments. Organic carbon content in the soil varied from 3.3 to 5.0 g kg -1 . It decreased from its initial value, when only 50 % NPK fertilizers was applied and under control treatment. While comparing the status of soil organic carbon, inorganic P and inorganic K fractions at surface and sub-surface soil depth, it was observed that except Ca-P fraction, all parameters decreased with increased soil depth. Amongst the inorganic P fractions, saloid bound-P constituted less percent of the other P fractions. The relative abundance of inorganic K fractions was in the order of water soluble-K < exchangeable-K < non exchangeable-K. Integrated use of fertilizers and organic manures maintained the sustainability of the pearl millet-wheat cropping system.