中亚热带红壤地区稻-稻-草轮作系统稻田土壤质量评价

Paddy soil quality assessment under rice-ryegrass rotation system in red soil region of mid-subtropics

在中亚热带红壤地区,利用定位研究方法,比较了5种不同的轮作模式,即早稻-晚稻-黑麦草、早稻-晚稻-黑麦草→早稻-晚稻-冬闲、早稻-晚稻-3/4黑麦草‖1/4紫云英、早稻-晚稻-紫云英、早稻-晚稻-冬闲,对稻田土壤质量的影响。研究结果表明,与常规稻作系统相比较,在稻-草轮作模式下,稻田土壤养分含量增加,物理性状改善,土壤生物活性提高,土壤动物数量增加。在对土壤功能评价的基础上利用土壤质量评价体系定量地评价了5种轮作模式的土壤质量状况。“水分贮存功能”(AW E)、“土壤结构退化抑制功能”(RSSD)、“稻田作物品质和产量维持功能”(SCOP)其评价值以及最终的土壤质量指数(SQ I)都是稻-稻-3/4黑麦草‖1/4紫云英、稻-稻-黑麦草、稻-稻-紫云英3种轮作模式大于常规稻作模式,其中以稻-稻-3/4黑麦草‖1/4紫云英表现最优;“促使水分运移、提高水分有效性功能”(FWM A)功能在5种轮作模式中其评价值相等。结果还表明,土壤质量指数(SQ I)、土壤退化指数(SD I)和生物肥力指数(B IF)之间具有良好的线性关系,说明此3种评价方法都能有效地评价研究试区稻田土壤质量。土壤退化指数(SD I)表明,稻-草轮作模式稻田土壤质量都有不同程度的提高,而常规稻作系统稻田土壤质量有轻微下降。稻田土壤蚯蚓丰富度与土壤质量指数(SQ I)、土壤退化指数(SD I)和生物肥力指数(B IF)都成显著的正相关,蚯蚓的丰富度可指示本研究试区稻田土壤质量。

Five different rotation systems, Viz. early rice-late rice-ryegrass （Loliun multiflorum）, early rice-late rice-ryegrass →early rice-late rice-winter fallow, early rice-late rice-3/4ryegrass ｜ 1/4Chinese milk vetch （Astragalus sinicus）, early rice- late rice-Chinese milk vetch and early rice-late rice-winter fallow, were established in red soil region of mid-subtropics. Five rotation models effects on soil characteristics were evaluated by measuring different physico-chemical, microbiological, biochemical parameters and soil animal. The results showed that, compared with conventional cropping system, rice （Oryza sativa）-ryegrass rotation systems improved paddy soil physico-chemical and biological properties as well as increased soil animal. Soil functions and soil quality assessment showed that, soil functions, viz. accommodate water entry （AWE）, resist surface structure degradation （RSSD）, sustain fieldcrop quality and productivity （SCQP） and soil quality index （SQI） were all higher under early rice-late riee-3/4ryegrass ｜ 1/4Chinese milk vetch, early rice-late riee-ryegrass and early rice-late riceChinese milk vetch than under early rice-late rice-winter fallow, the assessment values being greater under early rice-late rice- 3/4ryegrass ｜ 1/4Chinese milk veteh; facilitate water movement and availability （FWMA） was equal among five rotauion models. The results also showed that, highly correlations between soil quality index （SQI）, soil degeneration index （SDI） and biological index of fertility （BIF） were also detected, suggeating these three methods were all feasible to assess paddy soil quality in this study area. In addition, soil degeneration index （SDI） also suggested that, compared to the waster land in this study area, paddy field increased to varying degree under all rice-ryegrass rotation systems and decreased slightly under conventional cropping system in the present study. There were also positive correlations between earthworm abundance of paddy soil and soil quality index （SQI）, soil degeneration index （SDI）, biological index of fertility （BIF）, indicating earthworm abundance can be used as indicator of paddy soil quality in this study area.