Monitoring the changes in soil-available phosphorus and potassium in different fertilization managements under different crop rotations

This research was conducted to study the effects of different soil fertility management scenarios include not planted, control without any fertilizer, application of P and K based on soil tests and application of Farmyard Manure (FYM) and Spent Mushroom Compost (SMC), on the status of soil-available phosphorus (P) and potassium (K) in eight consecutive crops at the Bakhtajerd Darab Agricultural Research Station from 2017 to 2021. The results showed that the amount of available P remained constant, in fertilizer application based on soil test treatment, probably due to the absence of a positive or negative balance. The integrated application of chemical and organic fertilizers significantly increased soil-available P compared with chemical fertilizers alone due to the high concentration of P in organic fertilizers. Depletion of K up to 11% was recorded in the control treatment due to the lack of use of K-containing fertilizers. By applying 20 t ha−1 of organic fertilizer every other year, the consumption of P and K fertilizers could be reduced by 50%. In general, it is concluded that the integrated application of organic and chemical fertilizers containing P and K helps in the sustainable management of these nutrients in the soil.