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  • rice  (6)
  • NH3 volatilization  (2)
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Nutrient cycling in agroecosystems 21 (1989), S. 95-107 
    ISSN: 1573-0867
    Schlagwort(e): Terbutryn ; copper sulfate ; pH ; acetylene reduction assay ; algal enumeration ; ammoniacal-N ; NH3 volatilization ; Oryza sativa L.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract The effects of the algicides terbutryn and copper sulfate on the potential for reducing the gaseous loss of NH3 from urea applied to rice were examined in experiments with 2 methods of N fertilizer management, 2 or 3 N rates, and 3 algicide treatments. The experiments were conducted during the 1986 dry and wet seasons in an experimental field at Pila, Laguna, Philippines. Copper sulfate had little effect as an algicide at the rate used, but terbutryn immediately reduced algal growth. The populations of species resistant to terbutryn probably increased, but terbutryn had no long-term effect on the total number of colony-forming units of algae. There was some evidence that terbutryn reduced photodependent N2 fixation as estimated by acetylene reduction assay. Terbutryn, when applied with urea 10 days after transplanting, reduced the maximum floodwater pH by 0.9 units or more for 7 d in the DS and by about 0.5 units for 8 d in the WS. Terbutryn increased the ammoniacal-N (AN) concentration in the floodwater 100% or more in the DS and 60% in the WS. The combined effect of terbutryn on the floodwater pH and AN concentration was reduced photodependent NH3 partial pressure (ρNH3), about 25% in the DS and 38% in the WS.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Nutrient cycling in agroecosystems 46 (1996), S. 189-193 
    ISSN: 1573-0867
    Schlagwort(e): available P ; green manure ; P source ; P uptake ; residual effect ; rice
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract To evaluate residual recoveries of fertilizer phosphorus (P) two field experiments were conducted in Quezon Province, Philippines during 1991 dry season, under irrigated condition. Average grain yield increase was 0.50–0.9 t/ha due to residual effects of inorganic fertilizer P, regardless of source. Residual effects of fertilizer P with Sesbania rostrata or alone increased grain yield by 0.3–1.0 t/ha over control. Significantly higher yields were obtained with S. rostrata fertilized with Morocco phospate Rock (MPR) and S. rostrata + MPR applied on rice than the control. Results revealed that there is a promising effect of residual P from the applied P sources in increasing rice grain yield. Total P uptake increased due to residual P from fertilizer P applied. Results suggest that increased P uptake increased dry matter and grain yield.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Nutrient cycling in agroecosystems 46 (1996), S. 195-203 
    ISSN: 1573-0867
    Schlagwort(e): available phosphorus ; green manure ; phosphorus source ; phosphorus uptake ; relative effectiveness ; rice
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract To evaluate alternative fertilizer phosphorus (P) sources in lowland rice, two field experiments were conducted under irrigated conditions in Quezon Province, Philippines during 1990–1991 crop year. In another field experiment fertilizer P recycling through a green manure crop applied in the succeeding rice, was studied. Addition of fertilizer P increased grain yield by 1.5–2.0 t/ha (46%) in 1990 wet season (WS) and by 1.6–2.1 t/ha (56%) in 1991 dry season (DS). However, fertilizer P source and application level did not effect grain yield significantly. Results indicated that the less water-soluble and less expensive partially acidulated phosphate rock (PAPR), phosphate rock (PR) and less reactive PR were as effective as the more soluble but more expensive triple superphosphate (TSP). The relative effectiveness (RE) of local guano was significantly lower than that of other sources of fertilizer P. Fertilizer P applied to a pre-rice Sesbania rostrata green manure increased rice grain yield by 1.5–1.9 t/ha during 1991 DS. Further, S. rostrata fertilized with Morocco phosphate rock (MPR) gave significantly higher rice grain yield than did rice fertilized with MPR applied alone. In the P source experiments Olsen method and Pi correlated better with growth attributes than Bray 2 P. Phoshours uptake did not differ significantly among P sources and levels. Results suggest that P uptake was improved with green manuring. Correlation analyses revealed a close correlation between P uptake and dry matter yield and P uptake and grain yield.
    Materialart: Digitale Medien
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  • 4
    ISSN: 1432-0789
    Schlagwort(e): Band placement ; 15N recovery ; Fertilizer N use ; Immobilization ; NH3 volatilization ; Wetland rice ; Urea ; Oryza sativa L.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Geologie und Paläontologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Alternative N-fertilizer management practices are needed to increase productivity and the N-use efficiency of flooded rice (Oryza sativa L.). In the 1987 dry season, a field study using 15N-labeled urea evaluated the effect of the time and method of fertilizer-N application on grain yield and N-use efficiency in transplanted and direct-seeded flooded rice. Conventional fertilizer application (broadcasting and incorporation) was compared with band placement of liquid urea and point placement of urea supergranules. With band or point placement, the grain yields were significantly greater, and the partial pressure of NH3 (pNH3) in the floodwater was significantly reduced. In the transplanted rice, conventional fertilizer-N application gave a 64% total 15N recovery and 38% crop (grain and straw) recovery. Band placement of liquid urea N resulted in 92% total and 73% crop recovery. In the direct-seeded flooded rice, a conventional N application gave 72% total and 42% crop recovery; band placement, 98% total and 73% crop recovery; and urea supergranule point placement, 97% total and 75% crop recovery.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 126 (1990), S. 227-235 
    ISSN: 1573-5036
    Schlagwort(e): Oryza sativa ; rice ; root length density ; soil impedance ; tillage ; water stress
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract The influence of various tillage methods on two wetland rice soils in the Philippines is reported. The soils differed principally in clay content, 38% for the clay loam (clayey, mixed isohyperthermic Entic Hapludoll) while 56% for the clay (clayey, mixed noncalcareous, isohyperthermic Andaqueptic Haplaquoll). This had a marked effect on their response to tillage and varying water regime. The clay soil, under field conditions, showed little change in pore size distribution or soil water behaviour with different tillage methods. Crop (Rice, Oryza sativa L., var. IR20) yields were unaffected by tillage. In contrast, tillage effects were very marked in the clay loam soil, which consisted of a greenhouse and a field trial. In the greenhouse, which experienced severe dry periods, wet tillage not only increased the moisture retentivity but also the soil impedance at soil matric potential (ψ)〈−0.01 MPa. Seasonal average ψ was 〈−1 MPa. Root length density decreased by 39% with dry tillage and by 56% with wet tillage compared with zero tillage. Grain yield however, did not vary with soil treatment. In the field, which experienced moderate dry spells, ψ varied between −0.13 and −0.48 MPa. Root length density was significantly reduced at soil impedance 〉0.75 MPa. Wet tillage increased soil moisture storage which minimized the soil impedance during the dry cycle more effectively than did dry tillage. The crop performed best under wet tillage and least under zero tillage. Wet tillage in this soil was more effective under moderate than under severe water stress conditions.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Plant foods for human nutrition 40 (1990), S. 123-130 
    ISSN: 1573-9104
    Schlagwort(e): rice ; grain quality ; inorganic and organic N fertilizers ; protein and lysine content ; season effect ; IR64
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract The effects of nitrogen fertilizer treatment and source (prilled urea, urea supergranule, fresh azolla, rice straw or sesbania or rice straw compost and their combinations) on grain quality were studied in the 1987 crops of variety IR64 at IRRI. Although fertilizer application improved grain yield, it improved protein content only in the case of urea supergranule, azolla and rice straw. Lysine contents of brown rice protein were similar in samples with no N fertilizer and those with the highest protein content in both seasons. Fertilizer treatment regardless of source tended to decrease weight and increase translucency of brown rice in both seasons. Effects on other grain properties were not consistent in both seasons. Season affected more grain properties than fertilizer treatment did, particularly translucency which was higher in the dry season than in the wet season.
    Materialart: Digitale Medien
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  • 7
    ISSN: 1573-5036
    Schlagwort(e): green manure ; nitrogen fixation ; phosphorus ; potassium ; rice ; Sesbania rostrata ; stem nodules
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract The stem-nodulating tropical legume Sesbania rostrata is a promising green manure species for low input rice-farming systems in lowland areas. However, its success as biofertilizer depends on its biomass production and N2 fixation. Nutrient imbalances and soils low in available nutrients can considerably affect biofertilizer production. Use of mineral N, P, and K fertilizers in growing S. rostrata as biofertilizer for lowland rice was therefore evaluated in pot experiments, and in the fields in Central Luzon, Philippines. Two soils low in Olsen P (3–7.3 mg kg−1) and exchangeable K (0.05–0.08 meq 100g-1) were used. Increasing amounts of N (0, 10, 20, 30, and 40 mg kg-1), P (0, 50, and 100 mg kg-1), and K (0, 100, 200, and 300 mg kg-1) were applied to S. rostrata grown in the greenhouse, whereas small amounts of N, P, and K fertilizers (30, 15, and 33 kg ha-1, respectively) were applied in the field. Mineral N application depressed nodulation and N2 fixation in roots. It however, stimulated nodulation and N2 fixation in stems. Applying 30 kg N ha-1 as urea increased total N accumulation by S. rostrata and yield of the subsequent rice crop (IR64). Applied P and K both stimulated growth, nodulation, and N2 fixation of S. rostrata. Nitrogen accumulation in P- and K-fertilized S. rostrata was about 40% higher than that in nonfertilized green manure. Thus integration of mineral N, P, and K fertilizers in a green manure-based rice-farming system can considerably improve biofertilizer production and increase rice grain yield.
    Materialart: Digitale Medien
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  • 8
    ISSN: 1573-5036
    Schlagwort(e): leaf elongation rate ; leaf water potential ; maize ; nitrogen ; nutrient uptake ; phosphorus ; potassium ; rice ; soybean ; transpiration rate ; water stress
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract A pot experiment was conducted in the greenhouse to determine and compare the responses of rice (Oryza sativa L. var, IR 36), maize (Zea mays L. var. DMR-2), and soybean (Glycine max [L.] Merr. var. Clark 63) to soil water stress. Leaf elongation, dawn leaf water potential, transpiration rate, and nutrient uptake in stressed rice declined earlier than in maize and soybean. Maize and soybean, compared with rice, maintained high dawn leaf water potential for a longer period of water stress before leaf water potential. Nutrient uptake under water stress conditions was influenced more by the capacity of the roots to absorb nutrients than by transpiration. Transport of nutrients to the shoots may occur even at reduced transpiration rate It is concluded that the ability of maize and soybean to grow better than rice under water stress conditions may be due to their ability to maintain turgor as a result of the slow decline in leaf water potential brought about by low, transpiration rate and continued uptake of nutrient, especially K, which must have allowed osmotic adjustment to occur.
    Materialart: Digitale Medien
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