Phosphorus and Potassium Management under Long-term Manuring and Fertilisation

摘要

Phosphorus (P) and potassium (K) play important role in yield sustainability as well as food security of the country. Data emanating from the long-term fertiliser experiments (LTFE) have shown that the continuous application of P increased the productivity of all the cropping systems across the country but there occurred build up of P in soil not getting transformed into yield increases; it is posing threat to the environment in terms of eutrophication etc. Phosphorus management strategy has to be modulated to re-utilize the accumulated P by reduction in P dose to half or skipping of P in alternate year from the fertiliser schedule of the kharif crops. Unlike P, application of K did not contribute much to increase the crop yields at least in the mica-rich alluvial soils of the country. However, in red soils (Alfisols) application of K is very essential, even more necessary than N dose, as crop cannot be grown without K addition. Though black soils (Vertisols) are considered to be high in available K status but the present studies indicate that crops are showing response to applied K in some of the soils. Studies also indicate that in almost all the soils external supply of K is needed for high sustained productivity of the cropping systems. Potassium balance sheet for the LTFEs indicates that majority of soils operate with negative K balance.