Soil And Tree Nutrient Status In Citrus Orchards In Southern Guangxi And Their Effects On The Quality Of Orah

The citrus industry in southern Guangxi is developing rapidly,and the production is still based on empirical fertilization,and the amount of fertilizer is large,lacking scientific guidance.At present,there were few studies on the soil and tree nutrients in the citrus orchards in southern Guangxi,and the existing research had a narrow sampling range and a small sample size,which lacked systematic research.In order to find out the soil and tree nutrient status in the citrus producing areas of southern Guangxi,103 orchards in 8 counties（cities,districts）of southern Guangxi were investigated.The number of soil and leaf samples were collected from Wuming District,Xixiangtang District,Shanglin County,Long’an County,Mashan County,Debao County,Laibin City,Zhongshan County were 33,9,10,9,6,9,20,7respectively.Then,the content of 10 elements such as soil pH,organic matter,alkali nitrogen and available phosphorus,and the contents of 11 elements such as nitrogen,phosphorus and potassium were determined,and the relationship between soil and tree nutrient levels was analyzed.In addition,33 fruit citrus fruits were sampled and analyzed for fruit quality（single fruit weight,soluble solids,total acid and other fruit quality indicators）.And analyze the relationship between fruit quality and tree and soil nutrient levels.The main results of the study were as follows:（1）Soil nutrient abundance in citrus orchards in southern GuangxiThe soil pH value in the southern Guangxi is 5.41±0.89,which was mainly distributed in the acidity and below.The pH value was lower than 5.5 and accounts for64.4%.The organic matter content was（15.89±7.42）g·kg^-1,and the low amount and below were 50.0%.The contents of N,P and K in the soil of southern Guangxi were（109.31±54.34）,（66.33±98.38）and（179.67±181.39）mg·kg^-1,respectively,and the contents of Ca and Mg were（1274.74±1695.70）and（50.59±41.70）mg·kg^-1,respectively.Fe,Mn,Zn,Cu,B content were（41.32±54.55）,（25.93±24.66）,（2.92±6.10）,（1.04±1.37）,（0.31±0.15）Mg·kg^-1,respectively.The lack of P,K and Ca contents coexisted with the excess.The low and below range were 24.0%,42.3%and 28.9%,respectively,while the high and above range are 19.23%,33.7%and 16.4%,respectively.The main distribution of Fe and Mn At the appropriate amount and high range and above,the appropriate levels were 30.8%and 46.2%,respectively,and the high and above range were 52.9%and46.15 respectively;the contents of N,Mg,Zn,Cu and B were insufficient,and the insufficient ratio were 55.8%,93.3%,93.3%,89.4%,and 92.3%,respectively.（2）Nutritional abundance of citrus leaves in southern GuangxiThe contents of N,P and K in leaves of southern Guangxi were（29.61±2.64）,（1.24±0.15）and（15.22±4.65）g·kg^-1,respectively,and the contents of Ca,Mg and S were（35.75±8.50）,（2.44±0.71）and（3.14±0.74）g·kg^-1,respectively.The contents of Fe,Mn,Zn,Cu and B were（109.12±35.51）,（109.12±35.51）,（20.74±7.68）,（39.51±80.72）,（108.28±37.35）mg·kg^-1,respectively.The lack of N,K and Cu contents coexisted with the excess.The low and below range were 16.4%,26.0%and12.5%,respectively,while the high and above range were 48.1%,31.7%and 54.8%,respectively.Fe,Mn And B content were rich,which were 64.4%,72.1%and 43.3%at appropriate range,and the high and above range were 28.8%,24.0%and 55.8%,respectively.P,Ca and Mg elements were mainly insufficient.The proportions at the appropriate range were 64.4%,71.2%and 47.1%,respectively,while the ratios at the low and below levels were 34.6%,26.9%and 51.9%,respectively.The S element content in most areas of the producing area were normal,at an appropriate amount,the horizontal ratio was 86.5%.（3）Nutrient and leaf nutrient correlation of citrus soil in southern GuangxiMost of the correlations between soil nutrients reached a significant level,and some reached a very significant level.Except for the negative correlation between organic matter and P,P and Ca,the rest were positively correlated.The correlation analysis between leaves showed that there were very significantly positive correlation between N and P,S and Cu,Ca and S,Mg and S and Zn,S and Zn,and Fe and Zn.There were significantly positive correlation between K and Fe.There were very significantly negative correlation between leaf N and Ca,K and Ca and Mg.Soil pH and leaf Ca,organic matter and leaf Cu;soil Ca and leaf Ca;soil Fe,Zn,Cu and leaf S;soil Fe,Cu and leaf Zn,soil P,K,Mg,Zn and leaf B were very significantly positive correlation.Soil pH,Ca and leaf P;soil Cu and leaf N;soil Mn and leaf Ca;soil P and leaf S;soil Zn and leaf Zn were significantly positive correlation.Soil pH and leaf K,Fe;soil Fe,Cu and leaf K were very significantly negative correlation.Soil Mg,Zn and leaf K;Soil Ca and leaf K;soil Mg and leaf Zn were significantly negative correlation.（4）Soil nutrient abundance in Orah orchards in southern GuangxiThe pH value of the soil in Orah orchards in southern Guangxi was 5.44±0.86,which was mainly distributed in the acidity and below.The pH value was lower than5.5 and accounts for 54.6%.The organic matter content was（13.65±5.77）g·kg^-1,and the low and below levels were 66.7%.The contents of N,P and K in soil were（94.40±40.96）,（80.48±114.37）and（191.86±150.99）mg·kg^-1,respectively,and Ca and Mg contents were（832.99±542）and（52.04±45.84）mg·kg^-1,respectively.Fe,Mn,Zn,Cu,B content were（37.90±30.69）,（2.34±2.64）,（2.34±2.64）,（0.90±0.63）,（0.29±0.16）mg·kg^-1,respectively.The lack of P and K contents coexisted with the excess,and the low and below levels were 24.2%and 42.4%,respectively,while the high and above levels were 21.2%and 42.4%,respectively.Ca was mainly distributed in the appropriate amount and low volume and below were 69.7%and 24.2%,respectively.Fe and Mn were mainly distributed at appropriate and high levels and above,the appropriate levels were 30.3%and 54.6%,respectively,and the high and above levels were 60.6%and 45.5%,respectively.The contents of N,Mg,Zn,Cu and B were insufficient,and the insufficient ratios were 63.6%,90.9%,90.9%,90.9%,and 93.9%,respectively.（5）Leaf nutrient abundance in Orah orchards in southern GuangxiThe contents of N,P and K in leaves of Orah were（29.82±2.65）,（1.26±0.14）and（13.73±4.04）g·kg^-1,respectively,and the Ca,Mg and S contents were（37.07±7.49）,（2.71±0.64）and（3.27±0.65）g·kg^-1,respectively,the contents of Fe,Mn,Zn,Cu and B were（99.83±24.45）,（62.44±28.24）,（19.04±4.58）,（41.26±57.72）,（109.54±40.41）mg·kg^-1,respectively.N,Cu and B were mainly distributed in the appropriate amount and above,the appropriate proportions were 30.3%,30.3%and 51.5%,respectively,and the high and above levels were 57.6%.63.6%and 48.5%,respectively.P,Ca,S,Fe and Mn were mainly distributed at appropriate levels,with ratios of 75.8%,84.9%,84.9%,90.9%and 87.9%,respectively.K and Mg were mainly distributed at appropriate levels and below,the appropriate levels were 51.5%and 60.6%,respectively,the low and below levels were 33.3%and 39.4%,respectively.（6）Fruit quality of Orah in southern GuangxiThe fruit quality of Orah:TSS 10.5%¹6.0%,average was 13.3%.TA 0.2%⁰.6%,average was 0.4%.Vc 10.20²2.00mg/100ml,average was 14.41 mg/100ml.The acid ratio was 24.00⁶3.68,the average value was 34.95.The single fruit weight was77.50¹80.60g,the average value was 143.39g.The fruit shape index was 0.71⁰.86,the average value was 0.79.The edible rate was 64.16%⁸2.00%,and the average value was 73.6%.（7）Correlation between soil nutrition,leaf nutrition and fruit quality of OrahSoil N and single fruit weight;soil Fe,Cu and fruit shape index;soil Ca and solid acid ratio showed significant positive correlation.Correlation between leaf nutrition and fruit quality:leaf N,S and edible rate were very significantly positively correlated,leaf P was significantly positively correlated with edible rate;leaf N was significantly positively correlated with TA;leaf N was very significantly negative correlated with solid acid ratio;leaf K was significantly negatively correlated with Vc.