Evolution of yellow soil fertility under long-term fertilization and response of corp yield

Objectives The changes of yellow soil fertility under long-term fertilization were studied and the fertilization patterns were compared, aiming to provide support for choosing scientific nutrient managements for a steady and sustainable agricultural production.

Methods The study was based on the long-term fertilization experiment, which has been carried out for more than 20 years by the Scientific Observing and Experimental Station of Arable Land Conservation and Agricultural Environment (Guizhou), Ministry of Agriculture. The ten fertilization treatments include CK, N, NP, NK, PK, NPK, 3/4NP + 1/4M, 1/2 NP + 1/2M, M and MNPK. The crop yields and topsoil properties were measured, and the change trends of soil fertility was assessed using the improved Nemoro index (IFI), and the stability index and sustainability index were used to evaluate the effects of soil fertility and crop yield.

Results Different fertilization treatments led to different trends of soil fertility after 20 years. The lowest IFI was in the treatment NK and the highest in the treatment NPK + M. The IFIs in CK and partially fertilized treatments N, NP, NK and PK were all lower than those in treatments 3/4NP + 1/4M, 1/2NP + 1/2M, M, NPK + M. The IFI index was positively correlated with soil properties, soil pH and the contents of available N, total P and total K significantly affected the IFI index. The IFI was positively correlated with crop yield, with a correlation coefficient of 0.704^** and a path coefficient of 0.716^*. High yield and high IFI were found in manure application treatments (3/4NP + 1/4M, 1/2NP + 1/2M, M, NPK + M), while low yield and low IFI were found in CK and partially fertilized treatments (N, NP, NK and PK). NPK and NPK + M treatments maintained high yield and high stability and sustainability, while CK and PK treatments led to low yield and low stability and sustainability.

Conclusions Soil fertility could be measured well by the Nemoro index, and long-term manure application increased both soil fertility and crops yields in yellow soils. Long-term balanced fertilization and manure application can maintain the high yield with high stability and sustainability.