Phosphorus availability to maize as influenced by organic manures and fertilizer P associated phosphatase activity in soils.
Laboratory incubation and green house studies were conducted to compare the P availability of organic manures and P uptake from organic manures by maize. Various organic manures viz. Poultry manure (PM), Farmyard manure (FYM), Green manure (GM) and Crop residue (CR) and graded levels of fertilizer P were applied in Samana sandy loam and Ladhowal silt loam soils and incubated for 7, 15, 30, 60 and 90 days. Samples were analyzed for P availability, P uptake and alkaline phosphatase activity. The overall, phosphatase activity, Paranitrophenyl phosphate (PNP h(-1)g(-1)), in the Ladhowal silt loam soil was higher than in the Samana sandy loam soil. As the level of inorganic P increased, the release of PNP h(-1)g(-1) soil also increased. Among different organic manures, PM registered the highest enzyme activity followed by FYM, GM and CR. Compared to 7 days incubation a slightly higher increase in PNP was noticed in samples from 90 days incubation in both soils. The differential phosphatase activity in the organic manures was further reflected in dynamic P availability. The highest amount of Olsen extractable P was in PM-treated soil followed by FYM, GM and field pea crop residue. Organic manure addition along with inorganic P, irrespective of the source, increased the Olsen extractable P throughout the incubation period. Total P uptake by maize increased with the increasing level of inorganic P in both soils. The highest uptake was obtained in PM-treated soil and lowest in the CR-amended soil. We conclude that PM more readily supplies P to plants than other organic manure sources.
Garg
Shipra
S
Department of Soils, Punjab Agricultural University, Ludhiana, India.
Bahl
G S
GS
D000469:Alkaline Phosphatase / Q000032:analysis; D001682:Biological Availability; D002119:Calcium Carbonate / Q000032:analysis; D002412:Cations / Q000032:analysis; D005308:Fertilizers; D006863:Hydrogen-Ion Concentration; D007194:India; D008372:Manure; D009930:Organic Chemicals / Q000032:analysis*; D010744:Phosphoric Monoester Hydrolases / Q000032:analysis*; D010758:Phosphorus / Q000032:analysis*; D063245:Plant Development; D012822:Silicon Dioxide; D012987:Soil / Q000032:analysis*; D003313:Zea mays / Q000378:metabolism*
D002412:Cations; D005308:Fertilizers; D008372:Manure; D009930:Organic Chemicals; D012987:Soil; D010758:Phosphorus; D012822:Silicon Dioxide; C045290:phosphorylphosphatase; D000469:Alkaline Phosphatase; D010744:Phosphoric Monoester Hydrolases; D002119:Calcium Carbonate