| 【Objective】 To investigate in depth the soil nutrients and fertility,the N and P stoichiometric characteristics and the content and distribution of each mineral nutrient element in jujube orchards under drip and flood irrigation in the southern Xinjiang,to clarify the radial variation of nitrogen(N)and phosphorus(P)stoichiometry and the content of each mineral nutrient element in jujube orchards,and to provide a theoretical basis for reasonable fertilization of jujube orchards in the southern Xinjiang.【Method】 Thirty-two jujube orchards around Tarim Basin were selected as sample plots,and soil samples of 0-20 cm,20-40 cm and 40-60 cm soil layers were collected.The contents of soil p H,soil organic matter(SOM),total nitrogen(TN),available nitrogen(AN),total phosphorus(TP),available phosphorus(AP),total potassium(TK),available potassium(AK)and Calcium(Ca),Magnesium(Mg),Ferrum(Fe),Zinc(Zn),Copper(Cu)and Manganese(Mn)elements were determined.The p H and nutrient contents and fertility of soils from 0-60 cm in Aksu,Kashgar,Hotan and Bazhou were studied using principal component analysis.Taking Hui jujube and Jun jujube as samples,the tree age was determined by destructive sampling and the tree rings were sliced and shredded.The interannual and stoichiometric changes of N and P were analyzed,and the contents and distribution of mineral nutrients K,Ca,Mg,Fe,Zn,Cu and Mn in the tree rings were analyzed.【Result】(1)The soil p H of jujube orchards in four prefectures of southern Xinjiang was higher than7,which was slightly alkaline soil.In 0-60 cm soil layer,the contents of soil organic matter,total nitrogen and available nitrogen in jujube orchards were listed as Aksu prefecture > Kashgar prefecture > Bazhou >Hotan prefecture,the contents of total phosphorus and total potassium were listed as Aksu prefecture >Kashgar prefecture > Hotan prefecture > Bazhou,and the soil available phosphorus was opposite.Soil p H showed weak variation,while the contents of organic matter,total nitrogen,total phosphorus,total potassium,available nitrogen and available potassium showed moderate variation.For soil available phosphorus,Kashgar and Hotan showed strong variation.The order of total soil nutrients in the four prefectures was Ca >Fe > Mg > Mn > Zn > Cu.The soil Ca content in Hotan prefecture > Kashgar prefecture > Bazhou > Aksu prefecture.Fe content in soil was found in the order of Bazhou > Hotan prefecture > Kashgar prefecture >Aksu prefecture.The soil Mg content was the highest in Aksu prefecture and the lowest in Bazhou.The soil Cu was the highest in Aksu prefecture and the lowest in Hotan prefecture.The contents of Zn and Mn in soil showed that Aksu prefecture > Kashgar prefecture > Bazhou > Hotan prefecture.According to the coefficient of variation,the contents of Ca,Mg,Fe,Zn,Cu and Mn in soil of jujube orchards in different prefectures all belong to moderate variation.(2)The contents of soil organic matter,total nitrogen,total phosphorus,total potassium,available nitrogen,available phosphorus and available potassium in orchards soil in Aksu,Kashgar,Hotan and Bazhou were decreased with the deepening of soil layer,and the differences between surface and deep layer were significant(p < 0.05).Soil p H increased with the increase of soil depths,but the differences were not significant(p > 0.05).The contents of Ca,Mg and Cu in the jujube orchards in Aksu,Kashgar and Bazhou decreased with the deepening of soil depths,while the contents of Ca,Mg and Cu in the jujube orchards in Hotan were the highest at 20-40 cm.The contents of Fe and Zn in soil decreased with the depths of soil layer in the four prefectures.(3)The results of principal component analysis showed that the first principal component reflected the contents of soil organic matter,total nitrogen,total phosphorus,total potassium and available nitrogen,and played a major role.The fertility index of the four prefectures was in the order of Aksu prefecture > Kashgar prefecture > Bazhou > Hotan prefecture.The soil fertility of the orchards in Aksu and Kashgar were at the "first class" level respectively.Bazhou and Hotan are "second class" and "third class" respectively.(4)With the increase of age,the concentrations of N and P under drip and flood irrigation in tree rings increased,and the value of N: P in the xylem of older tree rings were higher than those in the newly grown rings.The N: P value of soil in Hui jujube orchards under drip and flood irrigation and Jun jujube orchards under flood irrigation showed vertical distribution characteristics: 0-20 cm > 20-40 cm > 40-60 cm.(5)The contents and distribution of mineral nutrient elements in the ring of red jujube showed different changing rules with the increase of the age of the trees.The contents of Cu,Zn and Mn showed an increasing trend,the contents of Ca and Mg showed a decreasing trend,and K content showing a general decreasing trend followed by an increasing trend.The changing rules of Fe content in Hui jujube and Jun jujube were not similar.Fe content in Hui jujube fluctuated greatly and showed a sudden peak between years,showing an irregular trend of change.The distribution regularity of Fe in the ring of Jun jujube was stronger than that of Hui jujube,which showed an increasing trend with the increase of age.(6)The annual average accumulation of mineral nutrients in the tree trunks of Hui jujube and Jun jujube showed the order of K > Ca > Mg > Fe > Zn > Cu > Mn.Both Hui jujube and Jun jujube showed that the annual average accumulation of K was the highest and the content of Mn was the lowest under drip irrigation.【Conclusion】 Nutrient indicators in all four prefectures showed that surface layers were higher than deeper soils;soil fertility was highest in the Aksu prefecture;in jujube orchards in the southern Xinjiang,soil organic matter,total nitrogen and available nitrogen contents were lower,and attention should be paid to strengthening the management and application of nitrogen and organic fertilizers.With the increase of age,the contents of N and P under drip and flood irrigation in tree rings showed an increasing trend,and the value of N: P in the xylem of older jujube was higher than that in the newly grown rings.The contents of Cu,Zn and Mn in red jujube showed an increasing trend with time,the contents of Ca and Mg showed a decreasing trend,the content of K showed a decreasing trend first and then increasing trend,the Fe in Hui jujube showed an irregular changing trend,and the Fe in Jun jujube showed an increasing trend. |
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