 หัวเรื่อง:การศึกษาสมบัติทางชีวเคมีของดินร้อยเอ็ดและดินพิมายที่ได้รับวัสดุอินทรีย์ ผู้เขียน: Patcharee Saenjan สื่อสิ่งพิมพ์:pdf AbstractA laboratory experiment to determine changes in chemical and biochemical properties of Roi Et and Phimai paddy soil receiving organic debris was conducted for both under field capacity and under submerged condition. The organic debris used were fresh Sesbania rostrata, rice straw and cow dung. The soil samples were incubated under field capacity and were analyzed for cumulative content of CO2, NH4+, and NO3- in the soil of 0-2.5 and 2.5-5 cm depths. The same treatments were incubated under submerged condition and were analyzed for pH, NH4+ , Mn2+ , Fe2+ and organic acid. In both soils, incorporation of organic debris increased NH4+ concentration in both aerobic and anaerobic conditions. Decomposition of organic debris increased in this order: Sesbania > rice straw > cow dung > control. The amount of CO2 and NH4+ were higher in Phimai paddy soil than in Roi Et soil. NO3- was increased while NH4+ was decreased in aerobic soil indicated nitrification. After submerging the soil, pH, NH4+ , Mn2+ and Fe2+ rose. This occurred more intense in Phimai soil than in Roi Et soil, especially, when organic debris were incorporated. Successive manganous and ferrous formation indicated maganese reduction and ferric reduction in submerged soil. Only acetic acid was detected as an intermediate product of organic matter decomposition. The amount of this acid increased to the maximum of 1.0 mM/100 g soil at 10 days after submergence in Roi Et soil receiving Sesbania and of 1.5 mM/100 g soil at 7 days in Phimai soil with Sesbania treatment, and finally decresed to the lowest amount at 24 days after submergence. This suggests that rice transplanting should begin at 2 weeks after incorporation of organic debris. |
หัวเรื่อง:การวิเคราะห์ลักษณะวันที่ฝนตกในภาคตะวันออกเฉียงเหนือ ผู้เขียน:Patcharee Saenjan, Charat Monkolsawat สื่อสิ่งพิมพ์:pdf AbstractApproximately 7.8 percent of the agricultural area in Northeast Thailand is irrigated with the remaining area under rainfed agriculture. Attempts to analyze characteristics of rainy days were carried out in order to understand the estimated rainfall characteristics of the Northeast. Analysis was made by comparing numbers of rainy days within the rainy season, mapping regional spatial rainy days and interpreting the coefficient of variation of rainy days and of no-rain days both spatially and temporally. Results of the analysis are summarized as follows: the periodical characteristic of rainy season could be divided into 4 periods: 1) a pre-rain period, from April 6 to May 3; 2) the first rainfall peak, from May 4 to July 10; 3) the second rainfall peak, from July 11 to October 7; 4) a post-rain period, from October 8 to October 17. It was identified that the large area of latitude approximately below 17? 12' 10" to the southern part of the region had rainy-day phenomena during the rainy season in accordance with the above characteristics of the first and the second rainfall peaks. Nakorn Phanom and Ubon Rachathani provinces had 100-110 rainy days. Intermediate numbers of rainy days were scattered all over the region. The zone of rainy day numbers lower than 60 rainy days occupies the west and some parts of the central also accompanied with high coefficients of variation. These parts of the region were in agreement with 135-150 no-rain days occuring during the rainy season which represented severe drought prone areas. In general, the coefficient of variation decreased with increasing the number of no-rain days, confirmed drought occuring in most parts of the northeast. |