Studies On The State Of Soil And Leaf Nutrient Element Contents Of Plants From Citrus Orchards In The Northwest Of Guangxi

Citrus were selected for the long-term mainstay industry of demonstration area, and it will play important role in agricultural production and everyday life of immigrants. In order to offer scientific basis for rational fertilizing, and improve high quality-yield. The status of trace element contents in the soil and the mineral nutrition status of citrus and correlation relation in the leaves were studied.The main results are as follows:1.Research was made on some indexes of soil in Northwest Guangxi. The soil indexes include soil organic matter, total Zn, Mn, Cu, Fe, Ca, Mg, available Zn, Cu, Fe, and exchangeable Ca, Mg, pH etc. Soil samples include 126 topsoils, which were collected in the citrus demonstration orchards of Kenfu demonstration plot. The status of second and trace element contents in the soil of citrus orchard were studied. The result showed that total Zn, Mn, Cu content was low, and total Ca, Mg content was seriously deficient, and however total Fe content was superfluous. Exchangeable second Ca, Mg were seriously deficient, available Cu content seriously deficient was 50.39%, available Zn content deficient, only 28.34% was in optimum range, however available Fe content was all higher.2.When soil pH was 3.75~4.65 ,very significant negative was found between the contents of available Fe and pH values in soil, however there no correlation between the contents of available Zn, Cu Ca, Mg and pH values in soil. Because the soil was strong acid that leads to Ca, Mg was deficient. There were a very significant positive correlation between the contents of available Zn, Cu, Mg and soil organic matter of citrus orchard, which indicated that improving soil organic matter help to soil nutrients status.3.The mineral nutrient status of citrus was studied by leaves analysis. The result indicated that P content and N content were mostly optimum status, K content was seriously deficient, however Ca, Mg content were mostly optimum status, but a few was deficient, Fe, Mn were optimum Cu, Zn content were generally seriously deficient in theleaves. By the result DRIS nutrition diagnosis of leaves, fertilizers should come in the order of K>P>Mg >Ca>N, and N: P : K: Ca : Mg=1:0.4:0.30:1.10:0.10.The preliminary studied suggests that the values of the optimum range of mineral element in the leaves of citrus orchards of Kenfu demonstration plot were :N2.9~3.5%, P0.12~ 0.16%, K0.8~1.70%, Ca3.0~4.6%, Mg0.30~0.49%, Fe50~140 mg-kg'1, Znl8~50 mg.kg-1, Mn20~100 mg.kg-1, Cu3-16 mg.kg-1, which may proved the parameters of nutrition diagnosis and rational fertilizing.4. Antagonistic and accelerate effect among major nutrition elements in citrus leaves were general, N and K, K and Ca were negative correlation, however there were positive correlation between N and P, N and Ca, Ca and Mg in citrus leaves. There were positive correlation was found between pH values in soil and the contents of K, but negative correlation and the contents of Ca. There was very significant positive correlation between the contents of N, K and soil organic matter of citrus orchard.5. Significant Correlation between mass tractions of mineral nutrient elements in leaves and corresponding soil were less, but correlation between mass fractions of mineral nutrient K, P ca, Mg, Mn, Zn in leaves and mass tractions of a few of nutrient of soil, which indicated that their relation was complexity. Leaves N and soil N were positive correlation, Leaves P and soil P were negative correlation, so should scientific rational fertilize P. The result showed the soil and leaf analysis mutual effect in nutrition diagnosis.