Split delivering phosphorus via fertigation to a calcareous soil increased P availability and maize yield (Zea mays L.) by reducing P fixation

Abstract

Phosphorus (P) fertilization methods significantly affect soil P availability, transformation, and crops yield. However, contradictory or paradoxical results are often available, and debates about this issue have never ceased so far. Therefore, the aims of this study are to explore influences of different P application methods on availability and transformation of added P in drip-irrigated system, and the responses of maize P uptake and its agronomic performances to P fertigation are also investigated. Here, we conducted a pot and filed experiments in drip-irrigated calcareous soil. Treatments included different P sources (phosphoric acid; polyphosphoric acid) with basal and split repeated application manners. Compared to the basal application, the average values of CDGT-P (P concentrations tested via diffusive gradient in thin films technique), Olsen-P, water-soluble P, and in situ P in the split repeated P application increased by 23.7%, 10.2%, 16.5%, and 34.4%, respectively (pot experiment). Furthermore, the average values of labile P (resin P and NaHCO3-P) and moderately labile P (NaOH-P) with the repeated P addition increased by 19.7% and 12.6%, whereas the concentrations of non-labile P lowered by 19.3%, respectively, relative to basal application treatment (pot experiment). The same trend was obtained in field experiment, implying that complete repeated P addition significantly increased P availability, reduced soil P transformation, and decreased P fixation. Therefore, a better agronomic performance of maize (P uptake, grain yield, and phosphorus use efficiency) was achieved in the complete repeated P application rather than basal application. Besides, diffusive gradient in thin film technique (DGT) was proved to be an accurate and powerful approach in testing soil available P. Our findings elucidate that repeated delivering P through fertigation method can be recommended as an effective P application strategy in drip-irrigated field, especially in semi-arid and arid regions. The feasibility of DGT method was certified and CDGT-P could well characterize plant-accessible P.