Multi-cropping systems often supports sustainable crop production and increases soil degradation. Seasonal fallow is one of the key and commonly used agricultural practices for soil restoration in the tropics. Nevertheless, our knowledge of the impacts and mechanisms of seasonal fallow intensity on enhancing soil fertility remains poor. Here, we conducted a 6-year site-specific field trial in the latosol zone of a tropical monsoon climate characterized by high temperatures and rainfall. This study aimed to assess changes in soil fertility across a typical seasonal fallow intensity gradient (i.e., rice (Oryza sativa L.)-rice-bitter gourd (Momordica charantia L.), RRB; rice-bitter bourd, RB; fallow-bitter gourd, FB; green manure (sesbania (Sesbania cannabina (Retz.) Pers.))-bitter gourd, GB). The results showed that soil organic C, total N, and C- and N-acquiring enzyme activities at 0–40 cm increased with seasonal fallow intensity. Further, the characteristic regional microbial P limitation was partially alleviated by green manure, attributed to the incorporation of fresh organic matter. Regarding soil fertility, FB and GB were 25.8–34.0 % and 57.6–67.7 % higher in topsoil than RRB and RB, respectively, while GB in the subsoil (20–40 cm) was 22.2–37.1 % higher than other treatments. Specifically, seasonal fallow intensities benefit soil fertility by regulating soil C and N, available P, and acid phosphatase activity. Moreover, the positive correlation between bitter gourd yield and soil fertility confirms the improvement in soil fertility caused by seasonal fallow. In conclusion, intensifying seasonal fallow, especially by including green manure, effectively boosts soil fertility without compromising crop yield in tropical multi-cropping regions.

中文翻译：

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季节性休耕强度的增加提高了热带多季作物区 latosol 的土壤肥力


多作系统通常支持可持续的作物生产并加剧土壤退化。季节性休耕是热带地区土壤恢复的关键和常用的农业实践之一。然而，我们对季节性休耕强度对提高土壤肥力的影响和机制的了解仍然很少。在这里，我们在以高温和降雨为特征的热带季风气候的 latosol 区进行了为期 6 年的特定地点实地试验。本研究旨在评估土壤肥力在典型的季节性休耕强度梯度（即水稻 （Oryza sativa L.）-米苦瓜 （Momordica charantia L.）， RRB;米苦鲈，RB;休耕苦瓜，FB;绿肥 （Sesbania cannabina （Retz.） Pers.））-苦瓜，GB）。结果表明，土壤有机碳、全氮、0—40 cm处的碳、氮获取酶活性随季节休耕强度的增加而增加。此外，由于新鲜有机物的掺入，绿肥部分缓解了特征性的区域微生物 P 限制。在土壤肥力方面，表层土壤中的 FB 和 GB 分别比 RRB 和 RB 高 25.8-34.0 % 和 57.6-67.7 %，而底土（20-40 cm）中的 GB 比其他处理高 22.2-37.1 %。具体来说，季节性休耕强度通过调节土壤 C 和 N、速效 P 和酸性磷酸酶活性来促进土壤肥力。此外，苦瓜产量与土壤肥力之间的正相关关系证实了季节性休耕对土壤肥力的改善。总之，在热带多季种植区，加强季节性休耕，特别是通过加入绿肥，可以有效地提高土壤肥力，而不会影响作物产量。