Management of chemical and organic fertilizer applications for decreasing the risk in rice production

Twenty one experiments were conducted during 2004-2008 at two locations in Ubon Ratchathani (Ban Donchi and Ban Khem) and two locations in Surin (Ban Nonkan and Surin Rice Research Center) to compare effects of chemical and organic fertilizer in single and combine applications. Each location had randomized complete block design with three replications of 10 treatments ( 3-4-4,6-4-4 kg of N-P2O5-K2O/rai, 1,000 kg/rai of 4 organic fertilizers which were rice straw compost (RSC1000), farmyard manure (FYM1000), green manure (GM1000), rice husk (RH1000), 500 kg/rai of each kind of organic fertilizer applied with N at the rate of 3 kg/rai: RSC500+3N, FYM500+3N, GM500+3N, RH500+3N). KDML105 rice variety was transplanted with 20*20 cm spacing (except 25*25 cm at SRNRRC). Rice grain yield obtained with 3-4-4 and 6-4-4 kg of N-P2O5-K2O/rai were not different from 1,000 kg/rai of RSC, GM and RH, correspond to rice yield of 379, 394,393, 390, 370 kg/rai respectively. Only the FYM1000 gave grain yield of 427 kg/rai higher than those of single application treatments. The greatest fertilizer response was FYM500+3N and GM500+3N which gave 431 and 422 kg/rai respectively. Although soil chemical properties were not improved by the application of chemical and organic fertilizer with an average over 4 locations of 5.0 soil pH, 0.6 percent organic mater, 5.1 mg/kg soil available P and 10 mg/kg soil exchangeable K. However, application of chemical with organic fertilizer especially FYM and GM was necessary in unfertile sandy soil.Summaries (En, Th)1 ill., 5 tablesผลการทดลองพบว่าการใส่ปุ๋ยเคมี อัตรา 3-4-4 และ 6-4-4 กก. ของ N-P2O5-K2O /ไร่ และใส่ปุ๋ยหมักฟางข้าว ปุ๋ยพืชสด และแกลบ อัตรา 1,000 กิโลกรัมต่อไร่ ให้ผลผลิตโดยเฉลี่ยไม่แตกต่างกัน โดยได้ผลผลิตเฉลี่ยตามลำดับดังนี้ 379 394 393 390 และ 370 กิโลกรัมต่อไร่ แต่การใส่ปุ๋ยคอก อัตรา 1,000 กิโลกรัมต่อไร่ ที่ให้ผลผลิต 427 กิโลกรัมต่อไร่ สูงกว่า กรรมวิธีที่กล่าวมาข้างต้น การใส่ปุ๋ยคอกและปุ๋ยพืชสดอัตรา 500 กิโลกรัมต่อไร่ ร่วมกับปุ๋ยไนโตรเจน 3 กิโลกรัมต่อไร่ ได้ผลผลิตข้าวเฉลี่ยจากทุกแห่ง 431 และ 422 กิโลกรัมต่อไร่ ตามลำดับ แม้ว่าผลวิเคราะห์คุณสมบัติของดินหลังการทดลองทุกปีพบว่าคุณสมบัติต่างๆ ยังไม่เปลี่ยนแปลง ค่าเฉลี่ยของจากทุกกรรมวิธีและทุกแห่งที่ทำการทดลองดังนี้ pH มีค่าเฉลี่ยเท่ากับ 5.0 อินทรียวัตถุ 0.6 เปอร์เซ็นต์ ฟอสฟอรัสที่เป็นประโยชน์ได้ 5.1 มิลลิกรัม/ดิน 1 กก. และโพแทสเซียม 10 มิลลิกรัม/ดิน 1 กก. อย่างไรก็ดี การใส่ปุ๋ยทั้งปุ๋ยเคมีและปุ๋ยอินทรีย์ มีความจำเป็นในการผลิตข้าวในดินนาที่ไม่อุดมสมบูรณ์ โดยเฉพาะใส่ปุ๋ยคอกหรือปุ๋ยพืชสดอัตรา 500 กิโลกรัมต่อไร่ร่วมกับปุ๋ยไนโตรเจน อัตรา 3 กิโลกรัมต่อไร

Growth of rice cultivars by direct seeding and transplanting under upland and lowland conditions

Rainfed rice crops are grown under both upland and lowland conditions. While upland crops are almost always direct seeded, both transplanting and direct seeding are commonly practiced for lowland crops in Asia. Direct seeding may be by broadcasting or dibbling. The effects of these various rice cultural practices on shoot and root growth and grain yield were examined using four contrasting cultivars in each of three years at Surin, Northeast Thailand. Under upland conditions, no yield was obtained under severe drought in two of the three years and yield was less than half that under lowland conditions in the third year. Lowland crops did not suffer water stress. Under lowland conditions, direct-seeded crops yielded more than transplanted crops in one year, slightly less in another when establishment was a problem in direct seeding, and similar between the two methods in the other. Direct seeding, particularly broadcasting, produced more total dry matter than transplanting. Root dry-matter growth was small after panicle initiation under all conditions, and was greater in direct seeding than transplanting in lowland conditions. Root growth occurred mostly in the top 10 or 15 cm soil layer in both upland and lowland crops. Root mass below 30 cm depth exceeded 10% of the total root mass at maturity in only one crop in which seeds were dibbled under upland conditions. Cultivar differences in root growth were generally small among all experiments. One notable exception was high tool mass near the soil surface for IR20, a cultivar suitable for irrigated conditions, when transplanted under lowland conditions. Although shoot growth was also similar among cultivars, there were often significant cultivar differences in grain yield. The highest yield was produced by IR57514-PMI-5- B-1-2, a semi dwarf cultivar that produced a large number of panicles in most experiments

Growth and grain yield of contrasting rice cultivars grown under different conditions of water availability

Rice crops are susceptible to drought, which causes large yield losses in many Asian countries. The development of drought-resistant cultivars may be assisted if mechanisms of drought resistance are known. This work was carried out to elucidate how some rice cultivars achieve higher yield than others under water-limiting conditions. A total of 11 experiments were conducted in northeast Thailand, and four contrasting cultivars were compared in each experiment for phenological development, dry matter growth, leaf death, grain yield and yield components. High-yielding cultivars were generally short statured and had high harvest index, and they tended to perform better than others in all conditions of water availability. When drought developed during late growth stages, early flowering to escape water stress was an important character. During late drought some cultivars were able to retain green leaves longer than others and increased dry matter when others stopped growing. It is thus concluded that cultivars suitable for rainfed conditions are those with high yield potential resulting from high harvest index under favourable growing conditions, appropriate flowering time to escape severe water stress that commonly develops after the end of the rainy season, and an ability to maintain growth during drought so that yield determining processes can be completed with minimum disturbance