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Subject: Soil Science × Author: Saha, Bholanath × End date: 2009 × Start date: 2009 ×
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    ThesisItemOpen Access
    Phosphate fractions and nutrients uptake by wheat as influenced by long-term P fertilization
    (2009) Saha, Bholanath; Tek Chand
    A long-term field experiment on pearl millet-wheat cropping sequence initiated in rabi in 1968 using split plot design was selected for present investigation entitled “Phosphate fractions and nutrients uptake by wheat as influenced by long-term P fertilization”. There were eleven treatment combinations related to sources (rock phosphate, nitrophosphate, SSP, DAP and UAP) and levels of P (60 and 120 kg P2O5 ha-1), including one control which were in main plots and three modes of P application were in sub-plots. Continuous application of different phosphatic fertilizers increased Olsen’s available P in soil. The maximum increase of available P was found with DAP (18.0 ppm) and minimum with RP (6.7 ppm). The available P content of the soil in control decreased from its original level 6.6 ppm to 2.7 ppm. Inorganic P fractions revealed that Ca-P was the dominant fraction (78.7%) followed by Al-P (10.1%), Fe-P (7.9%) and saloid-P (3.3%). Increasing levels of P application increased significantly saloid-P, Al-P, Fe-P and Ca-P over lower levels of P application. Irrespective of sources, levels or modes P application, grain yield of wheat increased significantly over control as well as of rock phosphate application. Increasing levels of P (60 to 120 kg P2O5 ha-1) increased the yield of wheat significantly. Cumulative mode of P application was found to be the best for grain and straw yield followed by direct and residual modes. All the water soluble phosphatic fertilizers were found superior over insoluble sources in terms of nutrients uptake by wheat. With increasing levels of P from 60 to 120 kg P2O5 ha-1, uptake of N, P, K and Mn increased significantly, whereas, the uptake of Fe, Zn and Cu decreased significantly. Saloid-P, Al-P and Fe-P fractions were highly inter-related and they all were significantly correlated with Olsen’s available P in soil. Olsen’s P, saloid-P and Al-P were positively and significantly correlated with grain yield (r = 0.829** to 0.894**), straw yield (r = 0.833** to 0.890**), P concentration in grain (r = 0.666* to 0.749*), and total P uptake (r = 0.860** to 0.928**) by wheat.