The Effect Of Long-Term Fertilization On Some Selected Physical, Chemical And Biological Characteristics In The Calcareous Fluvo-Aquic Soil

Soil fertility descended, tilth quality degenerated currently. The effects of long-term fertilize on soil quality and estimated soil quality was attended abroad. Use soil mass nutrient element as the indicator disaccord with the yield sometimes. In order to analysis and evaluate the soil fertility accurate, we need to consider soil fertility composition and affect factors, systemic estimate soil fertility.The study was carried out based on the long-term fertilization experiment which started in 1979 in Malan Farm, Xinji city, Hebei province. Different fertilization pattern including: control (no manure or fertilizer) mineral fertilizer alone, organic manure alone and combination use of mineral fertilizer and organic manure was performed since the beginning of the experiment. Soil nutrient element, some selected soil physical-chemical index, soil microflora, soil microbial biomass, soil enzyme activities were determined to studied the effect of long-term fertilization on soil fertility and soil biochemistry characteristics. Moreover, the adsorption and desorption of soil phosphate was selected as an example to study soil nutrient adsorption characteristic under long-term fertilization. Statistical method was adopted to evaluate the comprehensive effect of soil nutrient, soil microbial index and soil enzyme activities on soil fertility. The main results summarized as follows:1. Long-term application of organic manure would significantly increase soil nitrogen, phosphorus content, soil organic carbon (SC), soil humus carbon (HC), and quantity of complex carbon (QC).2. The amount and proportion of soil organic-mineral complex took a great change under 26-years of different fertilization. Application of organic manure would decrease easy dispersible G₀ and G_0-a, increase steady G₁ and G₂, and transform G₁ to more stable G₂, in favor of soil structure maintain; mineral phosphate fertilizer alone has the same trend; G_0-a was the special component of soil organic-mineral complex in calcareous fluvo-aquic soil. It played an important role in soil structure and nutrient supply or fixation.3. Organic manure application could remarkably decrease phosphorus adsorption and fixation. Phosphorus adsorbed by soil was more easily released with the organic manure treatments than the mineral fertilizer treatments. The potassium added to soil would increase phosphorus fixation, it was in favor of phosphorus transformation to more steadily forms. But this deleterious effect was well corrected by combination use of organic manure and mineral potassium fertilizer.4. Effect of long-term fertilization on soil microbial biomass: Organic manure application increased the amount of microbial effectively, include bacteria, fungi, actinomyces, Combine use of nitrogen with organic fertilizer increased bacteria, fungi was affected by phosphate markedly; Organic manure application increase the content of soil microbial biomass carbon, microbial biomass nitrogen, the soil microbial quotient(BC/TC)and the ratio of microbial biomass carbon and microbial biomass nitrogen, and decrease the ratio of soil C/N; The correlation of soil microbial indexes such as BC, BN, bacteria, fungi, actinomyces, and soil respiration intensity were significant, all these indexes could reflect soil microbial characteristics. These soil microbial indexes were highly correlated with soil nutrient (Organic, Total N, Olsen-P, and available N) and soil organic carbon indexes (HC, SC, QC).5. The effect of long-term fertilizer on soil enzyme activities: Application of organic manure could remarkably increase soil enzyme activities except catalase. Invertase and protease were affected by soil organic manure application, phosphate fertilizer application would inhibit the activity of alk-phosphatase, urea application would abduct the activity of urease. Soil microbial indexes affected soil enzyme activities in the order as: urease> alk-phosphatase> invertase> protease> catalase; Soil organic carbon indexes affected enzyme activities in the order as: urease> invertase> protease> alk-phosphatase> catalase; Soil organic matter affected soil enzyme activities in the order as: urease> invertase> protease> alk-phosphatase> catalase. The relationship of soil nutrient and soil enzyme activities: Olsen-P and alk-phosphatase was negative correlated; Soil total N was negative correlated with protease and urease.6. Principal component analysis and systemic clustering method were adopted to evaluate the soil quality of long-term fertilization: Principal component analysis could effectively reduce variable number, guaranteeing almost absolute information reflected by all original variables. Systemic clustering method could categorize soil quality according different soil quality indexes. The systemic clustering using three category indexes gave the same result. The result through systemic clustering using principal indexes was the same as the original indexes.