| Organic carbon is the core of soil nutrients and the basis of crop growth and development,and exogenous addition is the key to increasing soil fertility,in order to explore whether different exogenous organic carbon addition affects the quality of crops by changing the soil nutrient distribution with carbon as the core.In this study,the functional group structure of carbon of different organic materials was clarified by 13C nuclear magnetic scanning method,and the soil nutrient properties such as the distribution of carbon,nitrogen and phosphorus,the distribution of aggregates and extracellular enzyme activities of the whole soil after tomato planting,as well as the fruit yield and quality indicators of tomatoes,were further analyzed,and the relationship between carbon components,soil nutrient distribution and tomato quality of organic materials was established in an overall manner,in order to provide a theoretical basis for the rational selection of organic materials.The results of this trial show that:（1）The average soil organic carbon（SOC）content of coir and black charcoal increased by13%and 14%,respectively,compared with no fertilization,respectively,and the addition of exogenous organic carbon such as coir and black carbon was more conducive to the accumulation of soil organic carbon after planting in clay tomatoes.In sandy soil,the soil organic matter content of black carbon（T3）and sheep manure（T4）increased significantly by 11%and 9%,respectively.In clayey soils,the addition of organic materials such as coir and black charcoal is more conducive to the accumulation of soil organic carbon.The addition of exogenous carbon,such as black carbon,shows good potential for increasing the organic carbon content in both clay and sand.（2）Soil p H value,total nitrogen content,total phosphorus content and total potassium content were reduced by different organic fertilizer treatments.The contents of available potassium,nitrate nitrogen and ammonium nitrogen in soil treated with coconut bran were significantly higher than those in other treatments,and significantly increased by 23.32%,27.98 times and 1.52 times compared with the control treatment without fertilization.（3）The addition of different exogenous organic materials reduced the aggregate content of soil silt and clay and increased the aggregate content of soil.Under clay condition,the water-stable aggregate content of soil macroaggregates（>0.25mm）added by rice husk increased significantly by 152.94%,while the silty clay content decreased significantly by 68.08%.In the case of sandy soil,the same rule was observed,and the content of water-stable large aggregates（>0.25mm）in the treatment of rice husk as exogenous carbon was the highest.Meanwhile,compared with other treatments,rice husk reduced the content of silt and clay aggregates in the sand,but there was no significant difference.There was no significant difference in soil aggregate organic carbon content.The content of total nitrogen in soil aggregates added by sheep manure was the highest in clay（4）In clay soil,the soil C:N added with black carbon was the highest,and the soil N:P treated with coconut bran as exogenous organic material was the highest.In sandy soil,the C:N ratio of sheep manure was the highest.Organic materials with higher aromatic carbon,such as black carbon and sheep manure,showed a good advantage in soil carbon sequestration.Adding rice husk organic fertilizer to clay is beneficial to the acquisition of soil BG,LAP+NAG and AP enzyme activities.In sandy soil,the BG activity of sheep manure treatment was the strongest.In the two soils,the soil tended to be limited by microbial nitrogen under the addition of various organic materials.（5）Under the conditions of organic materials addition,black carbon and sheep manure with higher aromatic carbon content significantly improved the average fruit quality of tomato.In clay soil,the average fruit weight of treated fruit added with organic material of sheep dung increased by 1.50 times compared with that without fertilization.In sandy soil,the organic material of rice husk is the best.In terms of soluble sugar content of tomato fruit,soluble sugar content of sheep feces in clay was significantly increased by 73.85%.In sandy soil,soluble sugar content of coconut bran was significantly increased by 26.84%.As for the sugar-acid ratio of fruits in clay,the sugar-acid ratio of fruits added with black carbon as exogenous carbon was significantly increased by24.70%.In sandy soil,the sugar-acid ratio of rice husk added with exogenous carbon increased significantly by 50.34%.In terms of total nitrogen of fruits,total nitrogen content of rice husk and coconut husk in clay increased by 4.32%and 3.85%,respectively,while total nitrogen content of coconut husk treated fruits in sand significantly increased by 33.79%.From all aspects,it is recommended to use organic fertilizers with high content of decomposition resistant aromatic carbon such as black carbon in clay,while it is recommended to use organic fertilizers with high content of rice husk alkoxy carbon that are easily decomposed in sandy soil.Thus,it is beneficial to soil organic carbon sequestration,increase soil carbon sequestration potential,improve soil structure,and improve crop quality... |
