| Due to long-term excessive application of chemical fertilizers and poor tillage,soil matrix and skeletal particles are in close contact or unstable aggregation,and can not form stable structures.The application of organic fertilizers has become one of the effective measures to improve the stability of soil aggregates.Through laboratory and field experiments,the effects of organic fertilizer types on soil organic colloid types and soil structure formation at different temperatures were studied,and the reasons for the differences of soil structure stability in different accumulated temperatures,The results showed that:（1）Both laboratory and field experiments showed that the amount of large aggregates and secondary aggregates increased by reducing the amount of powder and clay,and the effect of straw was better than that of compost.Among them,the number of aggregates>2mm and0.25-2mm increased by 231.00%and 14.57%in indoor test,32.14%and 10.78%in field test,49.45%and 28.14%in indoor test and 11.66%and 9.68%in field test.（2）After applying organic fertilizer,the organic groups in soil macroaggregates and secondary aggregates increased,while those in straw treatment increased mainly in-OH,（CH3）2CHR,saturated aliphatic ether C-O-C,while those in composting treatment increased mainly in C=O,aromatic ring C=C,aromatic C=N.Organic groups in microaggregates and powder clays decreased slightly under straw treatment,but the composting treatment was comparable to the control.。The trend of inorganic anions in different levels of aggregates in composting treatment is similar to that in straw treatment,which increases in large aggregates and decreases in powder and clay,but the variation is small.Because the amount of-OH,（CH3）2CHR,saturated fatty ether C-O-C and other groups formed under straw treatment is large,and the amount of aromatic groups formed under composting treatment is relatively small,the MWD and DMD of straw treatment are higher than those of composting,and the stability of soil aggregates is stronger.（3）Within 77 days of application of organic fertilizer,the aggregate content of 0.25-2mm was the same as that of 25%,0.053-0.25mm was the same as that of 10℃and the aggregate content of>2mm and<0.053mm was higher than that of 10℃at 25℃and there was no difference between 10℃and 25℃treatment.The formation of large aggregates and powder and clay was less affected by temperature,lower temperature was beneficial to the formation of secondary aggregates,while higher temperature was beneficial to the formation of secondary aggregates Formation of microaggregates.The content of aggregates>2mm,0.25-2mm at 10℃was higher than 25℃,while the content of aggregates<0.05 mm and 0.053mm was lower than 25℃.That is to say,lower temperature was more conducive to the formation of macroaggregates and secondary aggregates,while higher temperature was not conducive to the formation of macroaggregates and secondary aggregates.（4）The aggregates of 0.25-2mm and 0.053-0.25mm treated at 10℃contain more aromatic ring C=C,aromatic C=N,C=O groups,which can form complex organic colloids;the aggregates of 0.25-2mm and 0.053-0.25mm have more formation of-OH and more formation of saturated aliphatic ethers C-O-C and（CH3）2CHR in the aggregates of 0.053-0.25mm at 25℃,which are more alkanes than those treated at 10℃.Simple,so MWD and GMD at 10℃are higher than those at 25℃.Temperature had no significant effect on the composition of aggregates<0.053-0.25mm.（5）Experiments in different accumulative temperature regions（Pingba and Weining）showed that after applying organic fertilizer,soil macroaggregates increased,secondary aggregates also increased,but the increase was less,and microaggregates and powder clays decreased.The application of organic fertilizer can promote the transformation of powder and clay,micro-aggregates to secondary aggregates and macroaggregates,and the effect of straw is better than that of compost.In the area with higher accumulated temperature,the stability of macroaggregates is higher than that in the area with lower accumulated temperature in a short time after applying organic fertilizer,but it decreases with time,even lower than that in the area with lower accumulated temperature.Under field test conditions,the differences between different accumulated temperatures and different types of organic fertilizer treatments were smaller than those in laboratory test. |
