Fares Ali, Bensley Adam, Bayabil Haimanote, Awal Ripendra, Fares Samira, Valenzuela Hector, Abbas Farhat
a College of Agriculture and Humans Sciences, Prairie View A&M University , Prairie View , Texas , USA.
b College of Tropical Agriculture and Human Sciences, University of Hawaii-Manoa , Manoa , Hawaii , USA.
J Environ Sci Health B. 2017 Jun 3;52(6):387-394. doi: 10.1080/03601234.2017.1292094. Epub 2017 Mar 3.
Soil moisture and organic matter level affects soil respiration and microbial activities, which in turn impact greenhouse gas (GHG) emissions. This study was conducted to evaluate the effect of irrigation levels (75% [deficit], 100% [full], and 125% [excess] of reference crop evapotranspiration requirements), and organic amendments (OA) type (chicken manure [CM] and bone meal [BM]) and OA application rates (0,168, 336 and 672 kg total N ha) on (i) soil physical properties (bulk density, organic matter content and soil moisture content) and (ii) soil carbon dioxide (CO) emissions from a highly weathered tropical Hawai'ian soil. Carbon dioxide readings were consistently taken once or twice a week for the duration of the cropping season. A drip irrigation system was used to apply the appropriate amount of irrigation water to the treatment plots. Treatments were randomly selected and corresponding organic amendments were manually incorporated into the soil. Plots were cultivated with sweet corn (Zea mays 'SS-16'). Soil moisture content within and below the rootzone was monitored using a TDR 300 soil moisture sensor (Spectrum Technologies, Inc., Plainfield, IL, USA) connected with 12 cm long prongs. Soil bulk density and organic matter content were determined at the end of the cropping season. Analysis of variance results revealed that OA type, rate, and their interaction had significant effect on soil CO flux (P < 0.05). Among the OA rates, all CM mostly resulted in significantly higher soil CO fluxes compared to BM and control treatment (p < 0.05). The two highest rates of BM treatment were not significantly different from the control with regard to soil CO flux. In addition, organic amendments affected soil moisture dynamics during the crop growing season and organic matter content measured after the crop harvest. While additional studies are needed to further investigate the effect of irrigation levels on soil CO flux, it is recommended that in order to minimize soil CO emissions, BM soil amendments could be a potential option to reduce soil CO fluxes from agricultural fields similar to the one used in this study.
土壤湿度和有机质水平会影响土壤呼吸和微生物活动，进而影响温室气体（GHG）排放。本研究旨在评估灌溉水平（分别为参考作物蒸发散需求的75%[亏缺]、100%[充分]和125%[过量]）、有机改良剂（OA）类型（鸡粪[CM]和骨粉[BM]）以及OA施用量（总氮0千克/公顷、168千克/公顷、336千克/公顷和672千克/公顷）对（i）土壤物理性质（容重、有机质含量和土壤湿度）以及（ii）高度风化的夏威夷热带土壤二氧化碳（CO₂）排放的影响。在作物生长季节，每周定期进行一到两次二氧化碳读数测量。采用滴灌系统向各处理小区施加适量的灌溉水。随机选取各处理，并将相应的有机改良剂人工混入土壤中。小区种植甜玉米（Zea mays 'SS-16'）。使用与12厘米长探头相连的TDR 300土壤湿度传感器（美国伊利诺伊州普莱恩菲尔德市Spectrum Technologies公司）监测根区及以下的土壤湿度。在作物生长季结束时测定土壤容重和有机质含量。方差分析结果表明，OA类型、施用量及其交互作用对土壤CO₂通量有显著影响（P < 0.05）。在OA施用量中，与BM和对照处理相比，所有CM处理大多导致土壤CO₂通量显著更高（p < 0.05）。BM处理的两个最高施用量在土壤CO₂通量方面与对照无显著差异。此外，有机改良剂影响了作物生长季节的土壤湿度动态以及作物收获后测得的有机质含量。虽然需要进一步开展研究以深入探究灌溉水平对土壤CO₂通量的影响，但建议为尽量减少土壤CO₂排放，对于类似于本研究中使用的农田，BM土壤改良剂可能是减少土壤CO₂通量的一个潜在选择。
