Purpose

Soil fertility plays a key role in citrus productivity. Therefore, it is necessary to explore the effects of soil amendments on soil fertility and citrus productivity and estimate carbon fractions’ suitability, which response to soil fertility and citrus productivity.

Methods

A field experiment in a citrus orchard was conducted containing five treatments: local habit fertilization (LF), special fertilizer [25% lower NPK than LF, (SF)], special fertilizer, and rice straw mulching [0%, 12.5%, and 25% NPK higher than LF (SFRS25, SFRS37.5, and SFRS50, respectively)]. Total organic carbon (TOC), microbial biomass carbon (MBC), water-soluble organic carbon (WSOC), permanganate oxidizable carbon (ROC), available N, P, K, fruit yield, and quality were analyzed.

Results

Straw mulching and special fertilizer significantly increased soil carbon fractions, such as MBC and ROC. Such treatments also enhanced the soil available N, P, and K, subsequently elevated the fruit yield. MBC, available K, and available P showed a significantly positive correlation with citrus yield. Redundancy analysis indicated that MBC and ROC significantly explained 61.87% of the variation for available nutrients, suggesting that the increase of organic carbon fractions and microbial biomass could accelerate nutrient cycling for the plant.

Conclusion

It proved that decrement application of special compound fertilizer with straw mulching raised fruit yield by altering soil carbon fractions to improve soil available nutrients or fertility. The MBC of soil labile carbon responded more sensitively to not only soil fertility but also citrus fruit yield.

中文翻译：

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土壤改良剂通过改变土壤碳含量对土壤肥力和果实产量的影响

目的

土壤肥力在柑桔生产力中起关键作用。因此，有必要探索土壤改良剂对土壤肥力和柑桔生产力的影响，并估计碳组分对土壤肥力和柑桔生产力的响应。

方法

在柑桔园进行了田间试验，其中包括五种处理方法：局部习惯施肥（LF），特殊肥料[比LF（NP）低25％的NPK]，特殊肥料和稻草覆盖[0％，12.5％和NPK比LF高25％（分别为SFRS25，SFRS37.5和SFRS50）]。分析了总有机碳（TOC），微生物生物量碳（MBC），水溶性有机碳（WSOC），高锰酸盐可氧化碳（ROC），有效氮，磷，钾，水果产量和品质。

结果

秸秆覆盖和特殊肥料显着增加了土壤碳含量，例如MBC和ROC。这样的处理还增加了土壤中有效氮，磷和钾的含量，随后提高了果实的产量。MBC，有效钾和有效磷与柑橘产量呈显着正相关。冗余分析表明，MBC和ROC显着解释了有效养分的61.87％变化，表明有机碳组分和微生物生物量的增加可以加速植物的养分循环。

结论

事实证明，秸秆覆盖减少特殊复合肥的施用可以通过改变土壤碳含量提高土壤速效养分或肥力来提高果实产量。土壤不稳定碳的MBC不仅对土壤肥力而且对柑桔产量都有更敏感的响应。