Abstract:
Objective Reducing phosphorus (P) content of organic fertilizer is of great significance to regulate the leaching risk of soil P in vegetable fields. But the potential of P-cutting of organic fertilizer is unclear to stabilize vegetable yield and decrease leaching loss.
Method The field experiment was carried out, using high P organic fertilizer(HP, P 2.03%)as a contrast, high-middle P organic fertilizer(HMP, P 1.75%), middle P organic fertilizer(MP, P 1.32%), and low P organic fertilizer(LP, P 1.06%)were tested for the effect on soil P leaching loss, soil P content and vegetable yield.
Result The early stage (the first and second crop) was the key period of P leaching loss. The leaching intensities of MHP, MP and LP reduced 4%, 21% and 31%( P < 0.05)compared with HP in the first stage, and 24%, 34% and 45% in the second stage, respectively. The soil total P content decreased 6.8%, 21.2% and 19.2%( P < 0.05)in the first stage, respectively. The soil available P decreased 0%, 21.6% and 20.0%( P < 0.05), respectively. The vegetable yield did not decrease significantly. The vegetable P contents of MP and LP treatments decreased significantly in the first stage. This study indicated soil total P was an alternately index to analyze the intensity of soil P leaching in in situ field. The leaching threshold was 1.19 g kg −1, MP and LP were the low leaching risk treatment, MHP and HP were high leaching risk treatment.
Conclusion The P-reduction organic fertilizer may significantly lessened soil P leaching loss intensity, significantly decrease the legacy of P in soil and didn’t decrease significantly vegetable yields. Using the soil P threshold value, the P reduction value and application patterns of organic fertilizer P content are recommended. Thus, it is recommended to use middle P organic fertilizer(P 1.32%)in soil with high P(Soil total P > 1.19 g kg −1), and high-middle P organic fertilizer(P 1.75%)in soil with low P(Soil total P < 1.19 g kg −1).