Đánh giá sự thay đổi hình thái phẫu diện, tính chất hóa học đất và khả năng cung cấp dưỡng chất NPK cho lúa trên đất phèn Đồng bằng sông Cửu Long.Đánh giá sự thay đổi hình thái phẫu diện, tính chất hóa học đất và khả năng cung cấp dưỡng chất NPK cho lúa trên đất phèn Đồng bằng sông Cửu Long.Đánh giá sự thay đổi hình thái phẫu diện, tính chất hóa học đất và khả năng cung cấp dưỡng chất NPK cho lúa trên đất phèn Đồng bằng sông Cửu Long.Đánh giá sự thay đổi hình thái phẫu diện, tính chất hóa học đất và khả năng cung cấp dưỡng chất NPK cho lúa trên đất phèn Đồng bằng sông Cửu Long.Đánh giá sự thay đổi hình thái phẫu diện, tính chất hóa học đất và khả năng cung cấp dưỡng chất NPK cho lúa trên đất phèn Đồng bằng sông Cửu Long.Đánh giá sự thay đổi hình thái phẫu diện, tính chất hóa học đất và khả năng cung cấp dưỡng chất NPK cho lúa trên đất phèn Đồng bằng sông Cửu Long.
THE MINISTRY OF EDUCATION AND TRAINING CAN THO UNIVERSITY SUMMARY OF THE DISSERTATION Major: Soil Science Major Code: 62 62 01 03 TRAN VAN HUNG EVALUATING CHANGES IN SOIL PROFILES, SOIL CHEMICAL PROPERTIES AND ABILITY TO SUPPLY NPK NUTRIENTS FOR RICE PLANTED ON ACID SULFATE SOIL IN MEKONG DELTA Can Tho, 2022 THIS DISSERTATION HAS BEEN COMPLETED AT CAN THO UNIVERSITY Supervisor: Prof Dr Ngo Ngoc Hung Assos Prof Dr Tran Van Dung The doctoral dissertation was evaluated by the Committees at the basic level Meeting at: At: Reviewer 1: Reviewer 2: The thesis could be found in: Learning Resource Center of Can Tho University National Library of Vietnam THE LIST OF PUBLISHED ARTICLES Tran Van Hung, Le Van Dang, Ngo Ngoc Hung, 2017 Effect of Phosphorus (P) blended with Dicarboxylated Acid Polymer (DCAP) on soil available P, rice yield and P uptake in acid sulfate soil Vietnam Journal of Agricultural Sciences, Vol 15 N0 4: ISSN 1859-0004 P (371- 379) Tran Van Hung, Le Phuoc Toan, Tran Van Dung, Ngo Ngoc Hung, 2017 Morphological and physicochemical properties of acid sulfate soils in Dong Thap Muoi Can Tho University Journal of Science, number of topics: Environment and Climate Change (2017) (2) ISSN 1859-2333 P (1-10) Tran Van Hung, Nguyen Quoc Khuong, Tran Ngoc Huu, Le Phuoc Toàan, Nguyen Van Nghia, Ngo Ngoc Hung, 2018 Studying of mineral nutrients uptake (N, P, K) in rice from dry season and N, P, K, Ca, Mg supplying capabilities from acid sulfate soil in Mekong Delta Vietnam journal of agriculture and Rural development 3+4/2018 ISSN 18594581 P (62-71) Tran Van Hung, Le Phuoc Toan, Tran Van Dung, Ngo Ngoc Hung, 2018 Studying the morphological and physico-chemical properties of acid sulfate soils in Cuu Long delta after 20 years cultivation Vietnam journal of agriculture and Rural development number of topics: Development of sustainable agriculture under the impact of climate change: challenges and opportunities august – 2018 ISSN 1859-4581 P (125-136) Chapter 1: INTRODUCTION 1.1 The necessity of the study The Mekong Delta has a relatively large area of acid sulfate soil (ASS), accounting about 1.6 million hectares Most of the acid sulfate soils are grown in rice, with low pH, high iron and aluminum toxicity which phosphorus fixation lead to difficult absorption for plants to limit factor in rice yield (Afzal et al., 2010; Paul et al., 2010; Qurban et al., 2015) Recently, a number of studies on NPK nutrients supplying to rice based on site specific nutrient management (SSNM) in the Mekong Delta that have been carried out to provide recommendations on fertilizers (Pham Sy Tan, 2005; Trinh Quang Khuong, 2005; Trinh Quang Khuong et al., 2010) At the same time, some other studies used the additive Avail@ polymer or the active ingredient (Dicarboxylic Acid Polymer- DCAP) cover on the DAP phosphate fertilizer to protect the phosphate particle to limit by toxic iron and aluminum in low pH, calcium and magnesium at high pH soil conditions The results show that Avail phosphate fertilizer application has increasing the efficiency of phosphorus and some crops yield (Dunn and Stevens, 2008; Mooso et al., 2012) Therefore, the assessment of the change in morphology, the variabilityin the quality of the acid sulfate soil and the ability to provide nutrients to rice on the acid sulfate soil to be considered 1.2 The objective of the study 1.2.1 General objective The study aimed to evaluate the change in soil profile morphology, the properties of acid sulfate soil and to determine NPK nutrient requirements for rice on acid sulfate soil in the Mekong Delta 1.2.2 Specific objectives To evaluate the change in morphological profile and chemical properties of acid sulfate soil in the Mekong Delta after 20 years of cultivation To determine the ability to supply NPK nutrients on rice of typical acid sulfate soils in the Mekong Delta To determine the efficiency of using phosphate fertilizer in the DAP mixed with Avail on rice of acid sulfate soil in the Mekong Delta 1.3 The activities of the study Content 1: Determining the change in morphology and chemical properties of acid sulfate soil in the Mekong Delta after 20 years for cultivation Content 2: Determining the ability to supply NPK nutrients to rice on typical acid sulfate soils in the Mekong Delta Content 3: Determining the efficiency of phosphate fertilizer in the DAP mixed with Avail for rice on acid sulfate soil in the Mekong Delta 1.4 The scientific and actual meaning of the thesis 1.4.1 The scientific of the thesis The results on the thesis have provided information about the change in morphology and soil chemistry after more than 20 years for cultivation Applying fertilizer method according to vacant lot to determine the ability for supplying nutrients N, P, K from soil and ability of rice yield by nutrients N, P and K in each experimental site on acid sulfate soil Experimenting results for applying P fertilizer of DAP mixed with Avail to determine the efficiency of phosphate fertilizer on acid sulfate soil on the Avail polymer active ingredient This is a valuable resource for research, study and teaching 1.4.2 The actual meaning of the thesis The results have determined the change in morphology and chemical characteristics on five acid sulfate soil profiles after 20 years cultivation However, soil classification based on diagnostic horizons and diagnostic properties of FAO-WRB soil name did not change The ability to supply nutrients N, P and K from the soil for summer- autumn and winter-spring rice crops at 04 experimental sites representing 04 ecological regions of acid sulphate soil in the Mekong Delta The results of applying phosphate fertilizer on DAP mixed with Avail only effective for rice in 01 site of heavily active acid sulphate soil 1.5 Subjects and scope of research 1.5.1 Research subjects The morphological and chemical properties of 05 typical acid sulfate soils in the Mekong Delta include (Hong Dan - Bac Lieu; Phung Hiep - Hau Giang; Tan Thanh - Long An; Thanh Hoa - Long An; Tan Phuoc - Tien Giang) Efficiency of using NPK fertilizer for rice on acid sulphate soil Efficiency of using phosphate fertilizer in the form of DAP mixed with Avail polymer active ingredient for rice on acid sulfate soil OM 5451 is a high yielding rice variety with a relatively short growing time (88 - 95 days), has high tolerance to alum 1.5.2 Research scope + In terms of space Research on acid sulfate soil morphology and characteristics in the Mekong Delta The study has organized in parallel of four experiments in the rice field for the ability of supply nutrients N, P, K and evaluation the effectiveness of Avail for rice representing on four ecological regions of acid sulfate soil in the Mekong Delta + In terms of time Evaluating the changes in morphological profile and chemical properties of acid sulfate soil in the Mekong Delta on two time periods (2015 comparing to 1992) Surveying on the ability to supply nutrients N, P, K and the effectiveness of DAP fertilizer mixed with active ingredient Avail for rice crops in Summer-Autumn 2014 and Winter-Spring (2014 - 2015) 1.6 New contributions of the thesis Determining the morphological change levels on acid sulfate soil in the Mekong Delta after more than 20 years for rice cultivation Evaluating the change in chemical properties on five typical acid sulfate soil profiles in the Mekong Delta after more than 20 years of cultivation Determining the ability to provide nutrients N, P, K from the soil and the ability of rice yield on nutrients N, P and K in the experimental sites on four ecological regions of acid sulfate soil in the Mekong Delta Evaluating the effectiveness of phosphate fertilizers on acid sulfate soil mixed with active ingredient Avail polymer Chapter 2: MATERIALS AND METHODS 2.1 Research materials (i) Materials Nitrogen fertilizer: Phu My Urea (46% N); Phosphorus fertilizer: Long Thanh Super (16% P2O5); Potassium fertilizers: Kali clorua (60% K2O); DAP fertilizer (18%-46%-0%); Avail@ polymer liquid concentration of 2‰ (ii) Field survey instruments and analysis (As presented in the thesis) 2.2 Study time and study area Conducting time: The study was carried out from 2015 to 2019 Morphological profiles of acid sulfate soil research site: Select 05 typical alum soil sample in the Mekong Delta for research (Table 2.1) Table 2.1: Location, Coordinates of soil profiles in 2015 Profil Symbol Profiles location Hong Dan district (now belongs to Phuoc HD-BL Long), Bac Lieu Province PH-HG Phung Hiep district, Hau Giang Province TT-LA Tan Thanh district, Long An Province TH-LA Thanh Hoa district, Long An Province TP-TG Tan Phuoc district, Tien Giang Province Coordinates (UTM-WGS.84) X Y 0532992 1029322 0567882 0613046 0630916 0641482 1080733 1175920 1176116 1158609 Study area: ability to provide NPK nutrients and determine the effectiveness of using DAP phosphate fertilizer mixed Avail for rice on typical alum soil in the Mekong Delta (Table 2.2) Table 2.1: Time of sowing and harvesting of rice in SA and WS at 04 experimental sites on acid sulfate soil in the Mekong Delta Notes: LXQ-Long Xuyen Quadrangle; HAD-Depressed Areas of The Hau River; CMPCa Mau Peninsula; PR-Plain of Reeds; (SA) Summer-Autumn; (WS) Winter-Spring 2.3 Hydrometeorology, farming system and seasonal calendar of alum land survey area (As presented in the thesis) 2.4 Laboratory soil characteristics (As presented in the thesis) 2.5 Research methods The relationship between the research contents on the alum land of the Mekong Delta (As presented in the thesis) 2.5.1 Content 1: Methods of surveying Soil Survey of natural elements and farming methods Interviewing the households where the site of digging for samples on the place, the history of land cultivation, solutions to renovate alum land Survey of geomorphology, climate, water level/aquatic level, wild plants Method of digging and describing morphology of profiles Use 2m trough drilling to re-explore the soil to choose the location representing the digger/soil profiles The size of the soil profiles is 1.5 m long, 1.0 m wide and 1.5 m deep Description of the soil on the plains, the description is prepared as the 2nd and 4th FAO's printed description "Soil Profiles Description Guidelines" (1998; 2006) Identify and re-describe the morphology of soil profile in 2015 and the research site in the period of 1992 Use a GPS to locate the longitude and latitude of the study point Method of collecting samples and analyzing of soil physicochemical Collect soil samples according to the soil layer, bring it to the processing laboratory to serve for analysis Based on the Handbook of analysis of soil, water, fertilizers, crops (Institute of Agriculturalization of Turkey, 1998) to collect soil samples for early analysis (method of analysis of physical and chemical targets of soil which was described in detail in the thesis) Soil Classification method Use the FAO-WRB soil classification system (2006) to classify and rename the soil for each soil profile Assess the change of some characteristics of acid sulfate soil Compare the morphological description results between two different times (2015 and 1992), find similarities and differences in targets of soil morphology Combine comparing soil characteristics to chart and evaluate the direction of change according to the soil layers phosphorus (0.82% P2O5) compared with the lack of phosphorus (0.71% P2O5) There was no statistically significant difference in potassium content in leaves, stems, and grains between the treatments with phosphate and SA season at sites in the Mekong Delta The potassium content in the leaves was 0.96% K2 O and grains 0.55% K2 O (detailed in table 4.4 of the thesis) 3.2.1.4 Effect of NPK fertilizers on total N, P, and K uptake in SA season Nitrogen is an important element in building proteins, cells, and plant tissues In SA season, the ability to supply nitrogen from the soil is low