Soil Nutrient Fertility in Citrus Orchards of Guangdong Province

Knowing the soil nutrient fertility is the basis to formulate a suitable fertilization strategy.Seventy soil samples in citrus orchards in Guangdong province were colleted,and N,P,K,Ca,Mg,S,Fe,Mn,B and Zn level was analyzed.Soil nutrient fertility status and its temporal variation in the citrus orchards were researched.The main soil constrains in citrus orchards were low Mg,B deficiency and unbalanced among K,Ca and Mg.Compared with late(1980's),P,Zn,K and N level rose greatly,Ca content decreased,and the other nutrients still remained similar level at present.Ca and Mg tended to be balanced at low level,however,unbalance between K and Mg was still present and even more severe.Significant positive correlations were shown between soil pH and nutrients.It was suggested that more Mg,B,lime or other alkaline fertilizer and less P be used in citrus orchards.