Variation of soil fertility under different years of continuous cropping and relation between continuous cropping duration and mulberry leaf yield

ObjectiveEffects of different continuous cropping years on soil fertility and relation between continuous cropping duration and mulberry leaf yield were studied,in order to provide references for soil nutrition improvement and sustainable development of mulberry fields. MethodThe field of nearly 15 years without mulberry planting was chosen as control,and soil organic matter,total nitrogen,total phosphorus,total potassium,available nitrogen, available phosphorus, available potassium and pH in rhizosphere soil under different mulberry growing years(5,10 and 15 years) were deter-mined and the relation between mulberry growing years and mulberry leaf yield was also analyzed. ResultSoil organic matter,total nitrogen,available nitrogen,available potassium,pH,available potassium/available nitrogen and available potas-sium/available phosphorus significantly increased(P<0.05, the same below) under both five years continuous cropping and 15 years continuous cropping treatments compared with CK. But soil total phosphorus,total potassium and available phosphorus,available potassium, available phosphorus/available nitrogen,available potassium/available nitrogen and avail-able potassium/available phosphorus significantly decreased under ten years continuous cropping treatment. Overall soil fer-tility level was the highest under 15 years continuous cropping treatment,followed by five years continuous cropping, and that under ten years continuous cropping treatment was lowest. Annual yield of mulberry leaf was the largest under ten years continuous cropping, reaching 40050 kg/ha, followed by that of five years continuous cropping and 15 years continuous cropping. Correlation analysis showed that soil organic matter had a significant positive correlation(P<0.01, the same be-low) with other nutrients. There were also significant positive correlations between pH and soil organic matter, total nitro-gen, available nitrogen as well as available potassium.There was significantly negative correlation between soil nutrient con-tent and mulberry leaf yield. ConclusionSoil nutrients in mulberry fields of continuous cropping are closely related to mul-berry leaf yield. Supplement of organic matter can increase organic matter in the soil, and balance soil nutrients and pH.