Neogi S, Bhattacharyya P, Roy K S, Panda B B, Nayak A K, Rao K S, Manna M C
Division of Crop Production, Central Rice Research Institute, Cuttack, 753006, Orissa, India.
Environ Monit Assess. 2014 Jul;186(7):4223-36. doi: 10.1007/s10661-014-3693-x. Epub 2014 Mar 8.
In order to identify the viable option of tillage practices in rice-maize-cowpea cropping system that could cut down soil carbon dioxide (CO2) emission, sustain grain yield, and maintain better soil quality in tropical low land rice ecology soil respiration in terms of CO2 emission, labile carbon (C) pools, water-stable aggregate C fractions, and enzymatic activities were investigated in a sandy clay loam soil. Soil respiration is the major pathway of gaseous C efflux from terrestrial systems and acts as an important index of ecosystem functioning. The CO2-C emissions were quantified in between plants and rows throughout the year in rice-maize-cowpea cropping sequence both under conventional tillage (CT) and minimum tillage (MT) practices along with soil moisture and temperature. The CO2-C emissions, as a whole, were 24 % higher in between plants than in rows, and were in the range of 23.4-78.1, 37.1-128.1, and 28.6-101.2 mg m(-2) h(-1) under CT and 10.7-60.3, 17.3-99.1, and 17.2-79.1 mg m(-2) h(-1) under MT in rice, maize, and cowpea, respectively. The CO2-C emission was found highest under maize (44 %) followed by rice (33 %) and cowpea (23 %) irrespective of CT and MT practices. In CT system, the CO2-C emission increased significantly by 37.1 % with respect to MT on cumulative annual basis including fallow. The CO2-C emission per unit yield was at par in rice and cowpea signifying the beneficial effect of MT in maintaining soil quality and reduction of CO2 emission. The microbial biomass C (MBC), readily mineralizable C (RMC), water-soluble C (WSC), and permanganate-oxidizable C (PMOC) were 19.4, 20.4, 39.5, and 15.1 % higher under MT than CT. The C contents in soil aggregate fraction were significantly higher in MT than CT. Soil enzymatic activities like, dehydrogenase, fluorescein diacetate, and β-glucosidase were significantly higher by 13.8, 15.4, and 27.4 % under MT compared to CT. The soil labile C pools, enzymatic activities, and heterotrophic microbial populations were in the order of maize > cowpea > rice, irrespective of the tillage treatments. Environmental sustainability point of view, minimum tillage practices in rice-maize-cowpea cropping system in tropical low land soil could be adopted to minimize CO2-C emission, sustain yield, and maintain soil health.
为了确定稻-玉米-豇豆种植系统中可行的耕作方式，以减少土壤二氧化碳（CO₂）排放、维持粮食产量并在热带低地水稻生态环境中保持更好的土壤质量，对砂质粘壤土中的土壤呼吸（以CO₂排放计）、活性碳（C）库、水稳性团聚体C组分和酶活性进行了研究。土壤呼吸是陆地系统中气态C流出的主要途径，也是生态系统功能的重要指标。在常规耕作（CT）和少耕（MT）方式下，全年对水稻-玉米-豇豆种植序列中植株间和行间的CO₂-C排放进行了量化，并同时测量了土壤湿度和温度。总体而言，植株间的CO₂-C排放量比行间高24%，在CT方式下，水稻、玉米和豇豆的CO₂-C排放量分别在23.4-78.1、37.1-128.1和28.6-101.2 mg m⁻² h⁻¹范围内，在MT方式下分别为10.7-60.3、17.3-99.1和17.2-79.1 mg m⁻² h⁻¹。无论CT和MT方式如何，CO₂-C排放最高的是玉米（44%），其次是水稻（33%）和豇豆（23%）。在CT系统中，包括休耕期在内，年度累计CO₂-C排放量比MT显著增加37.1%。水稻和豇豆的单位产量CO₂-C排放量相当，这表明MT在维持土壤质量和减少CO₂排放方面具有有益效果。MT条件下的微生物生物量C（MBC）、易矿化C（RMC）、水溶性C（WSC）和高锰酸盐可氧化C（PMOC）比CT分别高19.4%、20.4%、39.5%和15.1%。MT条件下土壤团聚体组分中的C含量显著高于CT。与CT相比，MT条件下的脱氢酶、荧光素二乙酸酯和β-葡萄糖苷酶等土壤酶活性分别显著提高了13.8%、15.4%和27.4%。无论耕作处理如何，土壤活性C库、酶活性和异养微生物种群的顺序均为玉米＞豇豆＞水稻。从环境可持续性角度来看，热带低地土壤的稻-玉米-豇豆种植系统可采用少耕方式，以减少CO₂-C排放、维持产量并保持土壤健康。
