Effect of water and P fertilizer coupling on corn yield, P uptake, and P utilization efficiency with drip irrigation in a calcareous soil

【Objectives】In drip irrigation agriculture system, according to phosphorus nutrition demand characteristic of maize in different growth stage, water coupling with P fertilizer application is an effective way of improving P resources efficiency as well as decreasing soil P fixation in calcareous soil. However, more information is needed about how to improve P utilization efficiency in drip irrigated fields. The objective of this field study was to compare the effect of different P fertilizers on drip irrigated corn yield and P utilization. 【Methods】 The experiment included four treatments: (i) no P fertilizer (CK), (ii) P2O5 81 kg/ha of solid diammonium phosphate (DAP) fertilizer basal applied at planting and 54 kg topdressed (T1), (iii) P2O5 81 kg/ha of liquid phosphoric acid (PA) fertilizer applied at planting and 54 kg topdressied (T2), (iv)P2O5 135 kg/ha of liquid PA topdressed (T3).【Results】The yield was 20622 kg/ha in the T3 treatment, 37% higher than in the CK, 25% higher than in the T1, and 10% higher than in the T2 treatment. The total biomass, grain number per panicle and grain weight per 1000 grains were also the highest in the T3 treatment (P0.05). At tasseling stage, 14.0 kg/ha of P was absorbed in the CK treatment, 22.7 kg in the T1 treatment, 21.0 kg in the T2 treatment and 18.3 kg in the T3 treatment. At maturity, total P absorption was 68.4 kg/ha, 77.8 kg/ha,.87.2 kg/ha and 91.9 kg/ha for CK,T1,T2, and T3, respectively. The amount of P absorption in the T3 treatment was significantly higher than in the other treatments (P0.05), indicating that topdressing of P significantly improved the P nutrition of corn. The apparent recovery efficiency of the P fertilizer (REP) was 16.6% in the T1 treatment, 32.6% in the T2 treatment and 40.6% in the T3 treatment. The T3 treatment increased REP by 8-24 percentage points compared with the T1 and T2 treatments. The agronomic efficiency of the P fertilizer (AEP) for T1, T2 and T3 was 7.9, 22.7 and 40.6 kg/kg respectively. The T3 treatment increased AEP by 17.9-32.7 kg/kg compared with the T1 and T2 treatments.【Results】 Liquid P fertilizer topdressing with drip irrigation significantly improves the P nutrition and P fertilizer utilization efficiency of corn, can be regarded as an efficient P fertilizer application strategy in calcareous soil.