Influence of Long-term Use of Fertilizers and Farmyard Manure on the Adsorption–Desorption Behaviour and Bioavailability of Phosphorus in Soils

Abstract

An understanding of the adsorptiondesorption behaviour of phosphate (P) in soils after three decades of long-term fertilization would be an invaluable supplement to our knowledge of the chemistry of P in soils and would assist in developing P application strategies for successive crops. With this objective and within the framework of a long-term experiment, we collected surface soil samples (0-0.15 m) from agricultural crop land on which a rotation of maize-wheat-cowpea (fodder) crops had been grown for 32 years. The soil samples were investigated for adsorption and desorption behaviour of P, and the buffering capacities of soil samples were computed from the adsorption data. Soils differed widely in their P supply characteristics. Phosphate adsorption increased while percentage P adsorbed decreased gradually with increasing levels of added P. Adsorption maxima and the extent of P adsorption was at its maximum in unfertilized soil, and P adsorption decreased with increased P applications. The incorporation of farmyard manure with optimal P levels decreased P adsorption even more than a super-optimal application of P fertilizers. Bonding energy and Freundlich constant 'n' also decreased with increased P application and with the incorporation of farmyard manure. The adsorption and desorption of applied P were inversely related, and the soils that adsorbed P the most readily released it the least into the soil solution, and vice-versa. Computation of maximum buffering capacities (MBC) indicated that increased levels of P application decreased MBC and increased P supply in soil. The beneficial effects of an annual incorporation of farmyard manure with optimal P levels were clearly pronounced, and P availability in these soils was found to be even higher than the soil receiving the superoptimal application of P fertilizers. Various adsorption-desorption parameters were significantly related with the P uptake of different summer (rice, maize, soybean) and winter (wheat, berseem and raya) crops. Adsorption maxima, desorption maxima and maximum buffering capacity are the major parameters governing P availability in soils.

Tillage and phosphorus management effects on enzyme-labile bioactive phosphorus availability in Cerrado Oxisols

“…The LVA showed the highest potential sorption capacity for phosphate, with S max values being 2 to 3-fold higher than those of the CR or LV soils. These results were in general agreement with the published literature (Anghinoni et al, 1996;Varinderpal et al, 2006). Varinderpal et al (2006) reported that P adsorption capacity in Indian soils is low, when compared to Brazilian soils, showing a P sorption S max of about 5.5 mmol kg − 1 in soils that had not been fertilized for over 20 years.…”

Relative contribution of different sized soil separates to inorganic P fractions in a Typic Ustochrept of N-W India

“…Accumulation of organic acids from decomposition of FYM would also compete effectively with orthophosphates for adsorption sites on Fe and Al oxides (Sanyal and Datta 1991) and thus render more P available in soil Table 3 Effect of long-term differential fertilization on Olsen-P and inorganic-P fractions (mg P kg À1 sand) in sand separates of soil solution. Beneficial effects of annual incorporation of FYM (much better even than super optimal application of P fertilizers) in these soils are reported elsewhere (Varinderpal-Singh et al 2006). Interestingly, the differences in Olsen-P content of sand particles in the subsurface layer of these treatments were not so distinct and might be attributed to nearly equivalent organic carbon contents of subsurface soil (Table 2).…”

Effects of 42-year long-term fertilizer management on soil phosphorus availability, fractionation, adsorption–desorption isotherm and plant uptake in flooded tropical rice

“…Higher adsorption in C 0 N 0 compared to rest of the treatments were ascribed to the presence of more exchange sites because of the 42-year stress on the soil P reserves for meeting crop requirements. The Olsen P content of C 0 N 0 was also lower than that of the fertilized soils, resulted in higher adsorption of P in C 0 N 0 soil [39]. The NPK treatment either alone or in combination with FYM showed lower adsorbed P than the other treatments.…”

“…It is interesting to note that P adsorption was lowest under the C 1 NPK treatment. This observation could be due to a relatively large amount of residual P in C 1 NPK [39]. The application of FYM played a key role in keeping the applied P in a more available form and, consequently, in reducing P adsorption.…”