| Farmland fertilization is the main cultivation measure and directly affects the elements of the circulation of farmland ecosystem.So that which leads the change of crop dry matter accumulation and restricts the formation of crop yields.Ecological stoichiometry theory,therefore,this paper discusses the elements circulation law of farmland ecosystem will help to explore the influence of human activities on the plant growth and development mechanism and provide a new method for realizing the farmland high effeciency and continuous production.In this paper we took the main economic crops to cotton of the Aral land reclamation area as the experimental material and constructed different gradient levels of soil N and P nutrient by N and P fertilization.On the basis of classical statistical analysis of different fertilizer leaves on cotton cotton and soil C,N and P ecological stoichiometric characteristics,we analyzed of cotton organs and soil C,N and P of seasonal change of the ecological chemical characteristics under different fertilizer,revealed circulation law of C,N,P element,verified whether the oasis cotton growth is or isn’t in line with the growth rate hypothesis,determined limitations element types of cotton,analyzed dynamic change of cotton dry matter accumulation along with the growth period,compared the cotton output in different fertilization treatments and aimed to reveal cotton the nutrients absorption characteristics of different growth periods in the Aral.The main conclusions were as follows:1.Under the setting of N,P fertilizer levels,the change rule of cotton C,N and P content and its ecological stoichiometric ratio were as follows: The maximum content of cotton C,N and P element appeared in N2 and P2,respectively.C contents were on the rise and the wadding stages decreased along with the growth period.N,P contents were on the decline along with the growth period.C,N and P contents in different organs under the influence of growth period were changed.The vegetative growth was main during seedling stage to budding stage,so that the elements mainlyaccumulated in the roots,stems and leaves.The elements mainly accumulated in grey,flower and boll and bolls during flowering and boll stage to boll opening stage.N:P was affected by the common of N and P element,indicating the nutrient balance between supply and demand relationship between plants and soil.The change of cotton N:P did not show the consistency rule along with growth period,the maximum of cotton N:P in leaves was in flower and boll stage during the whole fertility period.This result was consistent with those results of N elements distribution by Li Yongqi.The flower and boll stage was a period of cotton rapid growth and a key period of cotton yield.Cotton nutrition and reproductive growth in hand in this stage.Leaves with obtaining energy and synthesizing photosynthesis product are plants’ assimilated organ and can be used to indicate the cotton growth restriction element type.2.Under the setting of N,P fertilizer levels,the change rule of soil C,N and P content and its ecological stoichiometric ratio were as follows: Soil C element contents were gradually declined with growth period and picked up in the boll opening stage.N,P element content increased firstly and then decreased in the whole growth stage.Soil C contents had no obvious change in the different fertilizer treatments.And soil N contents were on the rise,soil P content had the same change rule along with the change of P adding level.Soil P contents decreased firstly and then increased in N fertilization treatments and soil N contents in P fertilizer treatments were the same.3.Under the setting of N,P fertilizer levels,C,N and P contents between in the cotton and soil relationship were as follows: Both presented a certain power function relationship between element contents.Nie Lanqin found that Pan Yanghu wetland plant C,N and P ecological chemical characteristics of leaves,litter and soil had a certain power function relationship.The results showed that the plant ecological stoichiometric ratio with soil N and P nutrient supply reflects the certain plasticity,inside the plant nutrient elements for stability study laid a foundation.4.Under the setting of N,P fertilizer levels,the change rule of cotton biomass were as follows: Cotton biomass showed a trend of the development of the "S" type and conformed to the Logistic growth model of growth function.The research resultsof the change rule of long-staple cotton biomass in southern Xinjiang by Zheng Deming and dry matter accumulation of upland cotton in Shihezi by Zhang Wangfeng showed that they were in line with "S" type curve.Using Logistic growth function fitted the dynamic processing of dry matter accumulation found that the maximum accumulation rate of N,P after the planting 99 d ~ 112 d and 95 d and 95 d,respectively.And increasing P fertilizer application extended the time of the dry matter accumulation so that cotton could make full use of the resources of field and would contribute to the formation and accumulation of cotton biomass.Dry matter accumulation between the different N,P treatments was N2 > CK > N3 > N1 > N0,P2 > CK > P3 > P1 > P0,respectively.5.Under the setting of N,P fertilizer levels,the change rule of cotton growth rate were as follows: Cotton growth rate increased then stability with the increase of soil N and P nutrient contents.Further exploration the relationship between cotton specific growth rate and the N:P and C: P showed that the cotton growth was in line with the growth rate hypothesis in Alar.However,Matzek and Hu Peilei found that the relationship between plant growth rate and its stoichiometric ratio of nutrient elements is not absolute.As a result of plant nutrient storage organs belies the relationship between its C,N and P chemical characteristics and growth rate that there is still not unified conclusion.That is to say,N: P ratio in leaves can be used to indicate limit element type of the cotton growth.According to N and P contents and the N:P ratio,the cotton growth was limited by N and P elements in this study.In the whole growth stage of cotton,the limiting element was gradually changed from P element to N element.6.Under the setting of N,P fertilizer levels,the change rule of the cotton yield and yield structure were as follows: Cotton boll number per plant and single boll weight increased along with the increase of soil nutrient contents and led to the improvement of cotton production.According to the fitting equation,the maximum cotton yield needed 793 kg/hm~2 of urea and its corresponding to the maximum yield was 5945 kg/hm~2.And the maximum cotton yield needed 571kg/hm~2 of Ca3(PO4)2and its corresponding to the maximum yield was 5951kg/hm~2.The results showed thatgetting every 100 kg seed cotton that the cotton needs to absorb the urea is about13.33 kg or 9.60 kg of Ca3(PO4)2.Increasing N fertilizer application caused the differences of boll number per cotton and single boll weight was the main reason that the discrepancy of cotton production in different fertilizer treatments.Fu Mingxin got the same results,also. |
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