Effect of Conservation Tillage Practices on Soil Phosphorus Nutrition in an Apple Orchard

Soil phosphorus(P) is an essential and limiting element for plant growth, which is significantly affected by different approaches to soil management. In order to reveal the effect of different management approaches on soil P and phosphatase activity in 0–20 cm and 20–40 cm soil, this research was conducted to study variations in the characteristics of P and phosphatase activity under 3-year tillage without mulching(CK), notillage with corn straw mulching(NTSM) and no-tillage with grass(NTG) in Liaoning apple orchard. The results showed that NTSM and NTG could significantly increase soil P content(P < 0.05) as compared with CK. However, the effect was different between NTSM and NTG; with the NTSM approach, the improvement in the P content in 20–40 cm was remarkable, and in the NTG approach, the improvement in the soil surface P content was significant. At the same time, soil phosphatase activity significantly increased(P < 0.05) under NTSM and NTG. The soil surface and 20–40 cm phosphodiesterase(PD) activity was enhanced under the two management approaches, however, the effect of NTG was stronger than NTSM. In addition, NTSM was more conducive to increasing alkaline phosphomonoesterase(Al P), and NTG was more conducive to increasing acid phosphomonoesterase(Ac P). Our findings highlight the variation of dominant mechanisms involved in soil P with different mulching materials application. NTSM and NTG could have the potential to increase P content and phosphatase activity, and provide a basis for using this method to improve P phytoavailability and reduce the application of soil fertilizer.