Yield stability in peanut-sweet potato rotation system under long-term combined application of chemical and organic fertilizers in latosolic red soil

Objectives Studying the effects of fertilization patterns on stability of crop yield is important for optimizing crop nutrient management.

Methods Two different experiments involving application of chemical fertilizer or combined application of chemical and organic fertilizers were conducted in upland (latosolic red soil) of Southeast Fujian for 15 and 13 years, respectively. The planting system in the two experiments was peanut-sweet potato rotation. The chemical fertilizer experiment was composed of no fertilizer (control, CK), farmer's practice (FP), recommended fertilizer (RF) and removal of either N, P or K in the RF. The chemical-organic fertilizer experiment was composed of CK, FP, RF, and replacement of one-third of N in RF with either commercial manure (CM), pig manure (PM) or rice straw (S). The sustainable yield index (SYI) and CV were calculated, and a grey linear model was established to quantitatively analyze long-term yield trend.

Results In the chemical fertilization experiment, the average yields of both crops (peanut 3936 kg/hm² and sweet potato 19070 kg/hm²), and their SYI (peanut 0.729 ± 0.019 and sweet potato 0.501 ± 0.028) were significantly higher under RF than those under the other treatments. The SYI of both crops under RF + PM treatment (peanut 0.689 ± 0.013 and sweet potato 0.514 ± 0.029) were significantly higher than those under RF and RF + S treatments, but similar with those under RF + CM treatment. According to the grey linear trend model, the average yield trend of peanut and sweet potato under RF treatment were 3780 kg/hm² and 19408 kg/hm², respectively, and they were significantly higher than those recorded under other treatments. The average yield trend of peanut under RF + PM (3492 kg/hm²) was significantly higher than those under RF, RF + CM and RF + S treatments. The average yield trend of sweet potato under RF + S (17567 kg/hm²) was significantly higher than those under RF and RF + CM, but not significantly different from that under RF + PM.

Conclusions Recommended fertilizer application (RF) can improve the yield stability of peanut and sweet potato in a rotation system. Replacing one-third of N in the recommended fertilizer with pig manure for peanut, or with straw or pig manure for sweet potato could enhance the yield trend level and the sustainable yield index in the long run.