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 หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Lime Application to Two Acidic Upland Soils for Soybean Production in Champasak Province, Lao PDR) ผู้เขียน: วงวิลัย เพงสุวรรณา,  ดร.ทัศนีย์ อัตตะนันทน์, ศาสตราจารย์ , Russell S. Yost สื่อสิ่งพิมพ์:pdf AbstractLow yield of soybean in the Lao People’s Democratic Republic (Lao) have been reported, where soil acidity could be one of the limiting factors affecting crop growth. In Champasak province, Lao, the effect of lime application on soybean production was studied on two acid upland soils, which varied in their chemical and physical properties. The NuMaSS software predicted that lime was needed and that the soil at the Bachieng site needed more lime than the Hoythakoune site. The results illustrated that liming had beneficial effects on soybean. The highest grain yields of soybean at the Bachieng and Hoythakoune site were 2,206 and 2,102 kg ha-1 compared with the control treatment, which yielded 1,462 and 962 kg ha-1, respectively. The results of the study indicated that lime had a strong effect on increasing soil pH, from 4.4 to 5.3 and from 4.7 to 6.0 for the Bachieng and Hoythakoune sites, respectively). The appropriate liming rates for soybean production at the Bachieng and Hoythakoune sites were about 1,710 and 550 kg CaCO3 ha-1, respectively. An economic dominance analysis indicated that the net return from liming was very high for both the Bachieng ($ 402 ha-1) and Hoythakoune ($ 503 ha-1) sites. |
หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Predicting Phosphorus Buffer Coefficients of Some Representative Soils for Maize Production in Lao PDR by Three Soil Analysis Methods) ผู้เขียน:ครปานี ดุ่นนาดี, ดร.ทัศนีย์ อัตตะนันทน์, ศาสตราจารย์, Russell Yost สื่อสิ่งพิมพ์:pdf AbstractPhosphorus buffer coefficient (PBC) is one of the important factors in the phosphorus fertilizer recommendation prediction by the use of Phosphorus Decision Support System (PDSS) program. A study on PBC of 7 representative maize soils in Laos and one Thai soil was conducted. The PBC determination was done by mixing the soils with potassium dihydrogen phosphate (KH2PO4) at the rates of 0, 25, 50, 100 and 200 mg P kg-1. All soil samples were kept in the incubator at 30 ?C for two weeks. The extractable P was analyzed by three methods: Bray-2, Mehlich-1 and iron oxide-impregnated filter paper method or Pi-test. The results showed different PBC values of soils with different extractants. Multiple regression analysis was used to determine the relationship between the PBC and soil properties. It revealed that PBCBray-2 was correlated with percentage of clay content with adjR2=0.64 and PBCPi-test was correlated with percentage of clay content and ammonium oxalate extractable aluminum, with adjR2 =0.89. The soil properties were substituted in the two models to predict the PBCBray-2 and PBCPitest, respectively. The predicted PBC was plotted against observed PBC to compare the prediction accuracy using soil properties by 1:1 line relationship. The result showed that the PBC should be estimated by Pitest for more accurate PBC prediction. |
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หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Predicting Phosphorus Buffer Coefficients of Representative Maize Soils in Laos) ผู้เขียน:ชัยสถิตย์ สุริยวงศ์ษา, ดร.ทัศนีย์ อัตตะนันทน์, ศาสตราจารย์, Russell Yost สื่อสิ่งพิมพ์:pdf AbstractMaize is an important crop in the Lao Peoples Democratic Republic (Laos) with as much as 113,808 ha grown in 2006. Recent research indicates that nearly all soils growing maize are deficient in phosphorus. In order to quantify the phosphorus requirement using the phosphorus decision support system (PDSS), the most important factor in the PDSS algorithm is the phosphorus buffer coefficient (PBC), which reflects the reaction of the soil to P fertilizer. The PBC was studied in 15 upland soils using the Bray 2 (PBCBray 2) and Mehlich 1 (PBCMehlich 1) methods and the iron oxide impregnated filter paper or Pi test (PBC Pi test) procedure. Multiple regression analysis was used to quantify the relationship between the PBC and some soil properties involved in the P-sorption process. The PBCBray 2 and PBCMehlich1 results were significantly correlated at the 0.01 levoerlg wanitihc carbon and iron having an adjusted R2 of 0.79 and 0.86 determined by the citrate bicarbonate dithionite method and the amount of clay, respectively. Unlike the two chemical extractions, the PBCPi test result was significantly correlated at the 0.01 level with aluminum (determined by the method using ammonium oxalate at pH 3 in darkness), the percent clay and organic carbon with an adjusted R2 of 0.80. However, the study suggested that the PBC should be estimated by the Mehlich 1 method, so that the model could more accurately predict the PBC. |
หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Nitrogen Mineralization and Different Methods of Ammonium Determination of Some Paddy Soils in the North, Central, and Northeast Regions of Thailand) ผู้เขียน:วาสนา เขาแก้ว, ดร.ทัศนีย์ อัตตะนันทน์, ศาสตราจารย์, Jongrak Chanchareonsook, ดร.ประภา ศรีพิจิตต์, รองศาสตราจารย์ , Russell Yost สื่อสิ่งพิมพ์:pdf AbstractHigh yields of rice are needed for farmer profitability and to provide this most important staple food and cash export crop of the country. Nitrogen fertilizer management is one of the key factors for high yielding of rice. Good management will reduce the contamination of the environment. Nitrogen mineralization or ammonium release after submergence is a useful index of nitrogen supplying capacity of the soils. The data is useful for effective fertilizer application. The study on ammonium release of 18 soil series which are the representative rice soils in the North, Central and Northeast regions of Thailand was performed. The results showed that ammonium release from 18 soils increased with time of submergence and the content reached the steady state at 4 weeks of submergence. The amount released of the soils followed the equation : Y = A-Be-ct except in the four soils. The higher ammonification percentage was found in soils lower in total N and clay content. Mehlich 1 and 0.25 M H2SO4 were the promising extracting solutions for assessing the initial amount of ammonium in the dry soils. |
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หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Nitrogen Fertilizer Response of Maize on Some Important Soils from DSSAT Software Prediction) ผู้เขียน:Nivong SIPASEUTH, ดร.ทัศนีย์ อัตตะนันทน์, ศาสตราจารย์, Russell Yost สื่อสิ่งพิมพ์:pdf AbstractTo lessen the environmental impact and cost of maize production, the efficient use of nitrogen fertilization is very important. Currently, the DSSAT software has been used to predict N fertilizer requirement of maize. However, the requirement of maize be to N fertilizer in some soils have been found to be lower than the amounts predicted by DSSAT. To use the predicted N fertilizer in some important maize soils of Thailand and Laos efficiently, field experiments were conducted on 4 representative sites. Two sites were on Lop Buri (Lb) and Pak Chong (Pc) soil series in Thailand, and the other two were on Saythong (St) and Bachieng (Bc) soil series in the Lao PDR. The results indicated that grain yields of maize grown on St and Bc soil series were increased with higher rates of N fertilizer while there was no response to nitrogen applications to maize grown on Lb and Pc series soils. These effects were attributed to N mineralization or nitrate release of the soils. From this study, the nitrate (NO3 - -N) release of Pc and Lb soil series were higher than those of St and Bc soil series, especially at the first period of incubation study in the laboratory. In the case of St and Bc soil series, the nitrate release of Bc soil was higher than that released from St soil, thus, resulting in the response of maize at the lower rate of N fertilization on Bc soil series. |
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