Mechanisms Of Soil Amendments On Pland Growth And Soil Properties Of Potato

In arid and semiarid regions, soil degradation which caused by irrational soil management with low water and nutrients retention capacity plays a crucial role in agricultural crop production in rainfed farming system, and efficient using the limited water resources, controling soil degradation and increasing yield and benefit is becoming the for sustainable agriculture development in these areas. Effect of soil amendments on potato growth and soil properties was investigated in a field experiment with three years’ continuous application of soil amendments, and treatments included potassium polya cry late (PAA), polyacrylamide (PAM) and humic acid (HA), both as single amendments, and compound amendments and a no amendment control. By studying the effect of soil amendments on soil physical, chemical and biological properties, we can definite its effect on soil water and fertilizer conservation; by studying the effect of soil amendments on morphological, photosynthesis, yield and quality, we can illustrate its effect on improvement of potato growth; by studying the effect of soil amendments on water use efficiency and benefit analysis of potato, we can evaluate its effect on sustainable agriculture development in rainfed farming system in arid and semiarid areas, and this will provide a theoretical basis and technical support for improving both yield and benefit in these regions. Base on the mechanisms of soil amendments on plant growth and soil properties, we can find out the appropriate soil management in these areas, soil amendments improve yield and soil properties of potato, this will be benefitial to utilize water resouces properly and control soil degradation.1. Soil amendments had a significantly (P<0.05) effect on morphological and photosynthesis. Soil amendments increaesed potato plant height, stem diameter, leaf area index, dry matter above ground and dry matter under ground repsectively by 0.49%-36.90%、2.59%-21.12%、1.85%-37.57%、4.65%-54.00% and 0.21%-83.07%, reduced root/shoot ratio in the early potato growing season by 0.85%-29.44%, and improved root/shoot ratio in the later potato growing season by 2.32%-32.56%; improved potato leaf soil plant analysis development value (SPAD), net photosynthesis (Pn), stomatal conductance (Gs) and transpiration (Tr) rates respectively by 1.4-17.0%,5.1-45.9%,2.4-90.6% and 2.0-22.6%, reduced intercellular CO2 concentration (Ci) by 2.1-19.5%.2. Soil amendments had a significantly (P<0.05) effect on physical, chemical and biological properties, improve soil water and fertilizer preservation. Soil amendments improved the soil moisture content in 0-40 cm soil layer by 2.23%-20.44%, reduced soil aggregate size fractions of<0.25 mm by 6.94%-37.22%,increased soil aggregate size fractions of>2.0 mm by 9.53%-32.43%, the effect of soil aggregate size fractions of 0.25-2 mm was not significant (P>0.05), decreased soil cone penetration resistance by 0.90%-39.68%, increased field water holding capacity by 0.68%-17.73%, and improved water storage in 0-40 cm soil layer in a certain degree; increased soil organic matter, available nitrogen, available phosphorus and available potassium respectively by 1.03%-11.20%n 0.82%-13.99%、1.24%-16.61% and 4.50%-22.20%; improved soil microbial biomass carbon, nitrogen and phosphorus respectively by 2.52%-27.29%、2.42%-28.09% and 3.48%-31.58%, improved soil catalase, invertase, urease and phosphate activity respectively by 4.09%-39.78%、4.45%-30.95%、3.66%-40.37% and 0.94%-29.80%.3. Soil amendments had a significantly (P<0.05) effect on potato yield and tuber quality, and improved benefit and ecological, it would contribute to improve both yield and benefit in rainfed potato production. Soil amendments affect different size tuber proportion, improved the proportion of tuber size>150 g by 1.72-16.56 percentage points, reduced the proportion of tuber size<75 g by 2.98-18.36 percentage points, increased potato fresh tuber yield by 4.24%-32.89%, there was no significant effect (P>0.05) on soil tuber nutrition quality within one year. Soil amendments increased potato water use efficiency by 4.13%-38.06%, some of the soil amendment treatments always improved the benefit, and the hightest value is 4947.1yuan per hectare. With the rainfed condition, soil amendments can contribute to efficient use of limited water resources and improve soil properties, and it is beneficial for the sustainable rainfed agriculture development in arid and semiarid areas.4. With different year and potato growing season, the effect of soil amendments on potato growth was influenced by both weather condition and the degree of potato vigorous growth. Meanwhile, the effect of soil amendments on potato growth was enhanced by increasing drought stress; the effect was also strengthened with the potato vigorous growth. The effect of soil amendments on soil physical, chemical and biological properties was enchanced and accumulated with the continuous application year increasing; the effect was fisrt increased then decreased in whole potato growth stage; the effect was reduced with the soil depth increasing.5. Both single and compound amendment treatments effectively affected plant growth and soil properties of potato. In single amendment treatments, the effect of HA on improving soil structure was better than PAA and PAM; the effect of improving soil water condition, PAM was the best among the three single amendments treatments, and HA was the worst. The effect of compound amendment treatments was better than single amendment treatments; this indicated that compound amendment treatments enhance the effect of soil amendments. Comprehensive analysis, the compound amendment treatment with PAM and HA showed the most promising in improving plant growth and soil properties of potato, but the economic return was not good; PAM always increased both yield and benefit of potato production, and provided the greatest improvement in economic return, it could be promoted to farmers in these regions for potato production.