Effects Of Long-term Fertilization And Land Use Patterns On Soil Microbial Characteristics On An Anthropogenic Loess Soil

This research was based on the long-term trial of “National Monitoring Base of SoilFertility and Fertilizer Efficiency on Loess Soil” in Yangling, Shaanxi province, and11treatments were chosen as no fertilizer (CK), only chemical N fertilizer (N), chemical N and Pfertilizer (NP), chemical N and K fertilizer (NK), chemical P and K fertilizer (PK), chemicalN, P and K fertilizer (NPK), chemical NPK fertilizer with straw return (SNPK, S representsstraw), chemical NPK fertilizer with low amount of cattle manure (M1NPK, M representsmanure), chemical NPK fertilizer with high amount of cattle manure (M2NPK), waste land(WL) and fallow land (FL). The effects of long-term fertilization and different land usepatterns on soil microbial characteristics were studied, such as soil microbial biomass, soilrespiration and soil microbial community functional diversity for the choice of rationalfertilization and land use patterns and soil sustainable utilization in loess area. The resultsshowed that:1. Compound organic and chemical fertilizers are the most conducive to improve soilorganic matter, total nitrogen and available nitrogen content, in which the effect of manureorganic fertilizer is better than that of straw return. Soil available P or/and available K contentwas significantly were significantly higher on treatments with P or/and K fertilizer, in whichthey were the most significantly increased on2treatments of compound manure and chemicalfertilizers. All treatments including N and P fertilizers together, whatever chemical fertilizerNP, NPK or compound organic and chemical fertilizers, could reduce soil pH significantly,which is helpful to improve soil acid-base property. In different land use patterns, long-termwaste land is the most remarkable to improve soil fertility, such as soil organic matter, totalnitrogen, available nitrogen and soil acid-base property.2. Long-term only chemical nitrogen fertilizer (N) reduce microbial quotient and the useof nitrogen for soil microbes significantly; To compare with CK, long-term NP and NPKtreatments could increase SMBC and SMBN, improve the microbial quotient, changemicrobial population structure significantly. Long-term compound organic and chemicalfertilizers (SNPK, M1NPK, M2NPK) were more conducive to improve SMBC and SMBN, inwhich the high amount of manure with chemical fertilizers (M2NPK) increased them most significantly, and could change microbial population structure significantly. Under differentland use patterns, long-term farmland fertilization (NPK) and waste land (WL) treatmentincreased SMBC and SMBN significantly.3. Among all chemical fertilizer treatments, soil base respiration rates of NPK and NPwere significantly increased, and soil cumulative respiration rate of NPK was higher than thatof CK significantly. The soil base respiration rate and cumulative respiration of SNPK,M1NPK and M2NPK were significantly increased, in which M2NPK was the highest. Therewere significant differences in soil base respiration rate and cumulative respiration betweendifferent land use patterns, in which WL was most conducive to increased soil biologicalactivity and metabolic intensity4. Long-term N was not conducive to maintain the soil microbial community diversity,but other inorganic fertilizers of which the long-term NP was most to help increase the carbonutilization, richness and dominance of species of soil microbial communities. On differentchemical fertilizer treatments, the main substrate carbon sources used by soil microbes weresugars, amino acids and carboxylic acids. Long-term compound organic and chemicalfertilizer treatments (SNPK, M1NPK and M2NPK) can significantly maintain the soilmicrobial community diversity, sugars and carboxylic acids were the main carbon sourcesused by soil microbes in compound organic and chemical fertilizer treatments; compared withbalanced fertilizer (NPK), organic and inorganic fertilizers no significant changes in soilmicrobial community diversity, thus, long-term balanced fertilizer (NPK) did not have anegative impact on soil microbial functional diversity. The carbon source utilization, richnessand dominance of species of soil microbes under long-term farmland fertilization and wasteland significantly increased, while fallow land was not conducive to maintain the soilmicrobial community diversity; Under different land use patterns, soil microbes mainly usesugars, carboxylic acids and amino acids carbon source.5. Correlation analysis showed that the richness and dominance of species,and carbonutilization displayed a highly significant positive or significant positive correlation withSMBC, SMBN, C/N and SMBC/SMBN, and a significant negative correlation with soil pH.Further multivariate linear regression analysis showed that soil microbial diversity wasmainly affected by total nitrogen(TN), available nitrogen(AN), available phosphorus(AP), pH,SMBN, C/N, SMBC/SMBN and available potassium(AK).