The rice-wheat cropping system covers a considerable area of the Indo-Gangetic Plain zone (IGPZ) due to agro-pedological compatibility. The nutrient requirements of the rice-wheat system in an organic mode are met through locally available organic matter (OM) is a subject of investigation from the viewpoint of declining the underlying mechanisms. A long-term organic farming experiment was carried out at the research farm of ICAR-Indian Agricultural Research Institute, New Delhi, India. Locally available sources of OM’s such as green manuring, green leaf manuring, farmyard manure (FYM), blue-green algae, and were evaluated for changes in soil physico-chemical properties and crop yield response after 15 years continuous applied of OM’s. Our results indicate that treatment involving applied green manure + farmyard manure + blue-green algae to rice + green leaf manuring + farmyard manure + to wheat [SFB(R) + LFA(W)] showed a sharp decline in soil pH by 5.5%, soil electrical conductivity (EC) by 24.0%, and soil bulk density by 14.0% over the control within the 0–15 cm soil depth. While, the treatment SFB(R) + LFA(W) improved the soil large macroaggregate (>2.0 mm) by 85.0% in 0–7.5 cm, and 92.8% in 7.5–15 cm in soil depth. Similarly, the treatment SFB(R) + LFA(W) showed 3.2-, 2.8-fold higher mean weight diameter (MWD) in corresponding soil depths of 0–7.5 cm, 7.5–15 cm compared to the control. Treatment SFB(R) + LFA(W) increased in soil organic carbon (SOC) holding by 5-folds in soil large macroaggregate, 4-folds by soil small macroaggregate (2.0–0.25 mm), 5-folds by micro-aggregate (0.25–0.053 mm), and 9-folds by silt + clay fraction (<0.053 mm) than control in 0–15 cm soil depth. These observations strongly support greater carbon recalcitrance with a higher half-life in soil silt + clay fraction than in other soil fractions. Further, treatment SFB(R) + LFA(W) maintained higher SOC by 79.4% and carbon stock by 76.6% over control in 0–15 cm soil depth. These responses on soil aggregates and SOC changes translated into significant crop responses. The treatment SFB(R) + LFA(W) thus, showed correspondingly higher grain yield (5.41 Mg ha and 4.69 Mg ha) of rice and wheat. Our study though showed on par agronomic response between low-quality OM’s and mixed-quality OM’s in 15-years. But considering the loading of SOC in the silt + clay fraction of soil, the study foresees a higher recalcitrant of SOC compared to any other soil fractions. This could well strengthen the process of soil aggregation having cascading response on other soil health-defined parameters a requisite for sustaining the rice-wheat sequence in the IGPZ.

中文翻译：

---

十五年的有机材料连续应用改善了土壤团聚、有机碳状况并维持了巴斯马蒂稻麦系统的生产力

由于农业土壤兼容性，稻麦种植系统覆盖了印度恒河平原区（IGPZ）的相当大面积。有机模式下稻麦系统的养分需求是通过当地可用的有机质（OM）来满足的，这是从减少潜在机制的角度进行研究的主题。印度新德里ICAR-印度农业研究所的研究农场进行了长期的有机农业实验。研究了当地可用的有机肥来源，如绿肥、绿叶肥、农家肥（FYM）、蓝绿藻，并评估了连续施用有机肥15年后土壤理化性质的变化和作物产量反应。我们的结果表明，施用绿肥+农家肥+蓝绿藻水稻+绿叶肥+农家肥+小麦[SFB(R) + LFA(W)]的处理显示土壤pH值急剧下降5.5% 0~15 cm土层深度内，土壤电导率（EC）较对照提高了24.0%，土壤容重提高了14.0%。而SFB(R)+LFA(W)处理使土壤大团聚体(>2.0 mm)在0~7.5 cm土层深度提高了85.0%，在7.5~15 cm土层深度提高了92.8%。同样，与对照相比，处理 SFB(R) + LFA(W) 在相应的 0-7.5 cm、7.5-15 cm 土壤深度中的平均重量直径 (MWD) 分别高出 3.2 倍和 2.8 倍。SFB(R) + LFA(W) 处理使土壤大团聚体的土壤有机碳 (SOC) 增加 5 倍，土壤小团聚体 (2.0–0.25 mm) 增加 4 倍，微团聚体增加 5 倍( 0.25-0.053 毫米），并且在 0-15 厘米土壤深度中，粉土 + 粘土部分（<0.053 毫米）是对照的 9 倍。这些观察有力地支持了土壤淤泥+粘土部分比其他土壤部分具有更高的碳不顺应性和更高的半衰期。此外，在 0-15 厘米土壤深度，处理 SFB(R) + LFA(W) 比对照保持较高的 SOC 79.4% 和碳储量 76.6%。这些对土壤团聚体和 SOC 变化的反应转化为显着的作物反应。因此，SFB(R) + LFA(W) 处理显示出相应较高的稻米和小麦产量（5.41 Mg ha 和 4.69 Mg ha）。不过，我们的研究表明，15 年来低质量 OM 和混合质量 OM 之间的农艺反应大致相同。但考虑到土壤中淤泥+粘土部分的 SOC 负载，该研究预计与任何其他土壤部分相比，SOC 的顽抗性更高。这可以很好地加强土壤聚集过程，对其他土壤健康定义的参数产生级联响应，这是维持 IGPZ 稻麦序列的必要条件。