Soil Fertilization and Maize-Wheat Grain Production with Alternative Sources of Nutrients

Abstract This study evaluated regional sources of nutrients to improve the soil fertility status and yield of maize-wheat succession in Southern Brazil. The treatments were: T1: no fertilization; T2: liming with dolomitic marble; T3: alternative liming (AL) with limestone interbedded with shale; T4: AL + 50% P - with Arad natural phosphate (P-ANP) + 50% P – triple superphosphate (P-TSP); T5: AL + 100% P-ANP; T6: AL + 100% P-ANP + 100% K-rich monzogranite; T7: AL + 100% P-ANP + 100% N from tung pressed cake (N-TPC); T8: AL + 100% P-ANP + 100% K-rich monzogranite + 100% N-TPC + 100% S; T9: AL + 100% NPK recommendation (urea, TSP and KCl). Immediate and residual effects were evaluated over 2.5 years (90, 360 and 900 d) on soil fertility and maize - wheat yield. The limestone interbedded with shale released Ca, Mg and corrected soil acidity similarly to dolomitic marble. The monzogranite increased the available K in soil, although improvements of the final product could enhance K release. The fertilization strategies used in T4, T7 and T8 presented a relative productivity index of 108, 111 and 108% when compared to T9 for maize plus wheat yield, while T3 (U$=1223) and T4 (U$=1284) resulted in higher profits (+4.2 and +9.4%, respectively) than T9 (U$=1174). The limestone interbedded with shale combined with 50% of P-ANP + 50% of P – TSP (T4) provided the best economical and technical results, highlighting the potential of selected rock powders for soil fertility correction and plant-nutrients supply.