Effects Of Salinity On Soil Microbial Activity And Soil Fertility In Cotton Field

Soil salinization more and more stress in the china, and the soil salinization is a key environmental stress factor that limits crop growth and population development, it is very important to exploit and utilize this soil. Two cotton cultivars with different salt-tolerance (CCRI-44, Sumian 12) were used, and five salinity rates (0:1.25 dS m-1,0.35%:5.80 dS m-10.60%:9.61 dS m-1,0.85%:13.23 dS m-1 and 1.00%:14.65 dS m-1), standing for five levels respectively were applied. The study focused on:(1) Effects of salinity stress on cotton field microbial biomass and soil nutrient content at different growth stages in cotton field; (2) Effects of salinity stress on cotton field soil microbial community diversity at different growth stages in cotton field; (3) Effects of salinity stress on cotton field soil iron content and microbe quantity and soil enzyme activity at different growth stages in cotton field. The main results were as follows:1 Effects of salinity on soil microbial biomass and soil nutrient content at different growth stages in cotton fieldUnder the same soil water treatment, with increasing of soil salinity, the content of soil microbial biomass C, N was decreased. At the same time, the growth of cotton was inhabited by soil salinity stress. Root dry weight, biomass, and seed cotton yield all declined with the increase of soil salinity, and the soil organic matter, total nitrogen, available nitrogen, available phosphorus and rapidly available potassium was decreased, but soil metabolic quotient was go up with the increase of soil salinity. Under the same soil salinity, the content of soil nutrient were much higher in well-watering treatment than in water stress treatment. Compared to Sumian 12, CCRI-44 was less affected by soil salinity at different growth stages of cotton. Correlation analysis showed that the soil microbial biomass C,N had a significant positive correlation with soil nutrient content(available nitrogen, available phosphorus and rapidly available potassium), and had a significant negative correlation with soil pH. 2 Effects of salinity on soil microbial community diversity at different growth stages in cotton fieldUnder the same soil water treatment, the average well color development with incubation times was increased, but average well color development, shannon index and richness index were decreased with increasing of soil salinity. Under the same soil salinity, the average well color development, shannon index and richness index were much higher in well-watering treatment than in water stress treatment. Soil water stress aggravated the effects of soil salinity stress. Compared to Sumian 12, CCRI-44 was less affected by soil salinity at different growth stages of cotton. Principal component analysis showed that six kinds of carbon source utilization rate was not the same affected by soil salinity at different growth stages of cotton, the carbohydrate was most.3 Effects of salinity on soil iron content, soil microbe quantity, soil enzyme activity at different growth stages in cotton fieldUnder the same soil water treatment, with increasing of soil salinity, the Na+, K+,C1-,Mg2+,Ca2+ content increased. But the the number of bacteria, fungi and actinomyces, ammonifying bacteria, the activity of urease, phosphatase, catalase decreased. At the same time, the growth of cotton was inhabited by soil salinity stress. Under the same soil salinity, the activity of soil enzyme, soil microbe quantity were much higher in well-watering treatment than in water stress treatment. Soil water stress aggravated the effects of soil salinity stress. Compared to Sumian 12, CCRI-44 was less affected by soil salinity at different growth stages of cotton. Correlation analysis showed that the activity of soil enzyme, soil microbe quantity had a significant negative correlation with soil Na+,Cl-, K+,Mg2+,Ca2+ content.