Dynamic changes of nutrient contents in orchard soil after pig manure application

Objective  Dynamic changes of nutrient contents in soil applied with pig manure were studied with the aim to offer guideline for reasonable manure application in litchi production.

Method  The variations of macro-, secondary and micro-nutrients in soils applied with different contents (w=0, 1%, 2% and 4%) of pig manure were investigated during 360 days of incubation test.

Result  In soil deficient of available N, P, K, Ca, Mg and medium of available Mn, Cu and Zn, after pig manure was applied at the content of 1%, the contents of all soil nutrients immediately reached abundant levels, except that exchangeable Ca and Mg contents reached medium levels. As the manure application rate increased, soil alkali-hydrolyzable N maintained at rich level with shorter duration and then decreased more sharply, while soil available P, K, Ca, Mg, Fe, Mn, Cu and Zn contents significantly increased (P<0.05). Moreover, soil nutrient (except available K and Fe) contents had larger fluctuations, leading to lower stability of soil nutrient supply.

Conclusion  Pig manure is a quality nutrient source for crop and is recommended to be applied at the rate of no more than 1%, namely 15 t·hm^–1 in litchi production. Simultaneously, the application rates of inorganic N and K fertilizers should be reduced, and some other inorganic fertilizers such as P, Fe, Mn, Cu and Zn should be withdrawn.