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Accueil du site → Doctorat → Chine → 2008 → Research of Soil Environment Effects of Alfalfa-Grain Rotation on Dryland Area of South Ningxia

Northwest University of Science and Technology (2008)

Research of Soil Environment Effects of Alfalfa-Grain Rotation on Dryland Area of South Ningxia

Liu Pei Song

Titre : Research of Soil Environment Effects of Alfalfa-Grain Rotation on Dryland Area of South Ningxia

Auteur : Liu Pei Song

Grade : Doctoral Dissertation 2008

Université : Northwest University of Science and Technology

Résumé
This paper takes artificial alfalfa grassland in The arid area of southern Ningxia as object of study. During 2004 2005 year, the soil moisture status of different year old alfalfas grasslands are mensurated in soil layer with 0 700 cm and 0 1000 cm . And during 2003 to 2005, with the 10-year-old alfalfa grassland as previous stubble and take spring wheat, millet and potato as rotation grains, a three-year alfalfa-grain rotation orientation experiment has been carried out in HaiYuan, south Ningxia. The differences of 27 kinds of rotation patterns have been analyzed and compared in crops water and nutrition use characteristic, crops total yield, water use efficiency(WUE), precipitation productive efficiency, nitrogen use efficiency(NUE), and soil nutrition and enzyme activety in the crop rotation end. Research conclusion has important theory and practice significance for grassland management and alfalfa-grain rotation in arid area of southern Ningxia .The main results of the study are as followings:1. Deep soil profile moisture of different growth age alfalfa fields has been measured during successive 2 years (2004 and 2005 years) in southern Ningxia dry area. Results indicate : With the increasing of alfalfa’s growth age, soil desiccation degrees intensify in whole. Average contain moisture rates in 0 700cm soil layer of 4,7,12 growth age alfalfa fields, which has measured in 2004, is in turn 5.30%、5.22% and 5.01% ; And those in 0 800cm depth of 3,6,10 growth age alfalfa fields, which has measured in 2005, is in turn 6.26%、5.60% and 5.27%. After 3 growth year, alfalfa taproot has reached under 300cm depth. So soil moisture of 300 800cm depth be consumed in intensity and 0 300cm soil moisture increase than before. According to moisture distribution and dynamic characteristics analysis on deeper soil profile of different growth age alfalfa fields, the soil profile be divided into four layers : Soil layer that moisture easy to change by precipitation and evaporation(0 100cm), Soil layer of precipitation continue to seep (100 to 300cm),Dry soil layer that water exhausted by alfalfa root system (300cm to 800cm) and layer regulated by water under deep soil that stored up(800 below 1000cm). Before 6 growth age, alfalfa’s soil moisture consumption depth and thickness are increasing by each year quickly. And in 6 growth age, both exceed 1000cm depth, and contain water in soil severely decrease, which 0 1000cm soil layer average moisture is only 5.73%. Alfalfa growth decline during its 7 12 growth age, soil moisture’s consumption depth and thickness are decreasing slightly, which contain moisture of 300 700cm dry soil layer only maintain 4% level, and those of 800 1000cm depth layer soil moisture has increase .2. Alfalfa-grain rotation has the feasibility in restores soil moisture of the degenerated alfalfa’s dry layer soil. In two consecutive years, the study measured the soil moisture content of farmland on which alfalfa had grown for different periods and the soil water content of farmland on which alfalfa had grown for ten years and then rotated with other crops in different years and then compared with the soil water content of those in different croplands. The study indicated that while alfalfa growth was prolonged the depth and thickness of the soil dry layer first increased and then declined. The depth of soil dry layer was 720 cm in the farmland with alfalfa growing for three years, at most 1000 cm in the farmland with alfalfa growing for six years , and 920 cm in the farmland with alfalfa growing for ten years and soil dry layer spanned from zero to nearly 700 cm soil in the farmlands with alfalfa growing for 3 12 years

Mots clés : Dried areas of southern Ningxia Alfalfa Soil dried layer Rotation of grass and field crops Soil moisture Soil nutrition

Présentation (Dissertationtopic)

Page publiée le 3 mai 2013, mise à jour le 10 janvier 2018