Effects of grass cover combined with different fertilization regimes on soil nutrients and enzyme activities in apple orchard in Weibei dryland, China.

The split-plot design was adopted in this experiment, with main treatments of grass cover and control and sub-treatments included four fertilization regimes: no fertilization, CK; manure, M; N,P and K fertilizer, NPK; and NPK fertilizer combined with manure, MNPK. Microplate fluorimetry was used to study the effects of grass cover combined with different fertilization regimes on the enzyme activities in apple orchard. The results showed that after mowing the grass (the residues were left on the soil surface as mulch), the soil water content, available P, nitrite nitrogen and the activities of βX, NAG, βG, CBH were increased compared to the control, with no significant differences for total nitrogen, soil organic carbon, and AKP activity. For grass cover treatment, the total nitrogen, soil organic carbon, and the activities of βX, NAG, βG, CBH, AKP were both improved before and after mowing the grass. However, the soil water content, available phosphorus, and nitrate nitrogen of grass cover treatment were lowe