Nitrogen mineralization ofSesbania sesban used as green manure for lowland rice in Sri Lanka

Sesbania sesban was evaluated as green manure crop for lowland rice in the Dry Zone of Sri Lanka. The legume was grown during a fallow period before lowland rice (Oryza sativa) and ploughed under just before transplanting. Weight loss and nitrogen content in litterbags containing leaves, stems and roots of the legume were monitored. Comparisons were made between rice yields from 20 m² plots after green manuring in combination with different nitrogen fertilizer levels (0, 2.4, 4.8 and 7.2 gm⁻²) and nitrogen fertilizer (9.6 gm⁻²) alone. Above-ground biomass ofS. sesban was 440 gm⁻² (dry wt) when ploughed under after 84 days growth. N-content in leaves, stems and roots was 3.76%, 0.41% and 0.73%, respectively. This gave a N-input fromS. sesban of 9.2 gm⁻² (8.3 g from above-ground parts and 0.9 g from roots). The corresponding K and P inputs were 7.3 and 0.6 gm⁻² respectively. The nitrogen rich leaves, which contained 88% of the nitrogen in the above-ground parts, decomposed and released its nitrogen much more rapidly than the stems and roots. After only four days the leaves had released 5.3 g Nm⁻² and after 14 days they had released 6.4 g Nm⁻². The highest rice yield (505 gm⁻²) was obtained usingS. sesban and 4.8 gm⁻² of N-fertilizer. The yields with only N-fertilizer or onlyS. sesban were 442 gm⁻² and 396 gm⁻², respectively. Due to the rapid decomposition of the nitrogen rich leaves,S. sesban did not behave as a slow release fertilizer. Thus, it is not necessary to apply nitrogen fertilizers as a basal dose.     

Effectiveness of Sesbania rostrata and Phaseolus calcaratus as green manure for upland rice grown in acidic soil

Two field experiments on green manuring were conducted under upland acidic soil (pH = 4.35) conditions with the following objectives: (1) to determine the influence of inoculation site, P fertilization, and liming on the biomass production, N content, N accumulation, and N availability of S. rostrata grown in an acidic soil, (2) to compare the effectiveness of S. rostrata, P. calcaratus and urea as N sources for upland rice as affected by liming and N source-sowing time combination, and (3) to assess the effect of liming and N source-sowing time combination on % Ndff (N derived from the fertilizer), % Ndfs (N derived from soil), % FNU (fertilizer N utilization), and FNY or fertilizer N yield (kg N ha^–1) of upland rice grown in acidic soil. At 2 weeks after incorporating S. rostrata (95 days after lime application), liming significantly increased N availability by more than 2-fold suggesting that the decomposition of S. rostrata by soil microflora was stimulated by lime. Liming, phosphorus application, and inoculation site improved significantly the dry biomass production, N content and N accumulation of S. rostrata; thus, enhancing its green manuring potential. Regardless of liming, S. rostrata whether applied at 0 week or 2 weeks before sowing was superior to urea in improving grain and straw yields. P. calcaratus when applied at 2 weeks before sowing also produced higher grain yield than urea. Immediate sowing of upland rice after green manure incorporation did not affect negatively the growth and development of upland rice; hence, farmers could save at least 2 weeks in their cropping calendar. N source-sowing time combination had a highly significant influence on % Ndff, % Ndfs, % FNU, N uptake, and fertilizer N yield of upland rice. However, only N uptake was influenced significantly by liming. The rice plant obtained significantly higher % Ndfs from the soils treated with green manure than those treated with urea regardless of liming. The % FNU and % Ndff from the green manures were 11-37% and 9-25%, respectively. These values are much lower than those obtained under continuously flooded soil conditions possibly because of the differences in the organic matter decomposer populations and N loss mechanisms between sloping upland conditions and continuously flooded conditions.     

Aeschynomene as green manure for rice

The widely accepted application of the fertilizers via the irrigation stream (fertigation) has necessitated the development of suitable techniques to help research in estimating the fertilizer requirements of crops. This paper describes a simple, inexpensive, and precise system tested for three years in field experiments, in which various levels of a fertilizer could be supplied simultaneously. The same system could also be used when irrigating simultaneously various crops with different fertilizer requirements from a single concentrated fertilizer solution, using only one fertigator.     

Azolla: Botany,physiology, and use as a green manure

This is a comprehensive review of literature pertaining to the aquatic fern Azolla and its nitrogen-fixing algal symbiont, Anabaena azollae. The preceding decade has witnessed an explosive growth in research on Azolla, and hopefully this paper will facilitate those efforts. The paper is broken into three major categories: botany, physiology and biochemistry, and agriculture. The botany section includes a world distribution map and reference tables for the 6 Azolla species, and includes the first review of literature on Anabaena azollae. The physiology and biochemistry section covers the range of topics from environmental factors to life processes and nitrogen fixation. Tables on the effect of growth regulators and on the rate of nitrogen fixation measured by acetylene reduction are presented. The agriculture section draws extensively from literature published in the People’s Republic of China and in the Democratic Republic of Vietnam. The major focus of this section is on the history and management practices for Azolla cultivation as a green manure for rice. The effect of weed suppression, use as a fish food and animal fodder, and the insects and diseases of Azolla are also discussed.     

绿肥配施氮肥对岩溶区稻田土壤微生物群落的影响

绿肥参与耕作改制是土壤培肥及作物增产的有效措施,对土壤微生物群落结构及多样性的影响至关重要。【目的】研究绿肥配施氮肥对岩溶区稻田土壤微生物群落结构的影响,阐明微生物、土壤生态环境因子及作物产量的相互关系,为岩溶稻区绿肥替代氮肥提供理论依据和数据支撑。【方法】以典型岩溶稻田土壤为研究对象,设置冬闲+不施氮肥(CK)、冬闲+氮肥(N)、绿肥+不施氮肥(M)、绿肥+氮肥(MN) 4个处理,通过3年田间定位试验,对土壤微生物进行高通量测序,解析不同施肥处理对细菌和真菌群落的影响。【结果】与CK相比,MN处理显著提高了早稻产量,提升了土壤有机质、全氮、碱解氮和速效钾含量,降低了速效磷含量。MN处理显著提高细菌群落丰富度及多样性,而真菌群落丰富度和多样性在MN处理有降低趋势。岩溶稻田土壤优势细菌类群主要为Chloroflexi、Proteobacteria和Acidobacteria等,优势真菌类群主要为Ascomycota、Basidiomycota和Zygomycota等。冗余分析(RDA)结果表明,土壤速效钾是影响土壤细菌群落组成的关键环境因子。共现网络分析结果表明,细菌-真菌群落交互关系主...     

Effect of NPK on growth and nitrogen fixation of Sesbania rostrata as a green manure for lowland rice (Oryza sativa L.)

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.     

长期双季稻绿肥轮作对水稻产量及稻田土壤有机质的影响

以中国农业科学院红壤实验站1982年布置的长期定位试验为研究对象,分析了长期双季稻绿肥轮作体系下水稻产量变化趋势、稻田土壤有机质变化特征及土壤活性有机质组成。结果表明,绿肥作物与双季稻轮作种植后,水稻产量显著高于冬闲对照,绿肥作物紫云英、油菜和黑麦草处理年平均水稻产量（1982-2008）分别为10.8 t?hm-2?a-1,10.2 t?hm-2?a-1和10.0 t?hm-2?a-1,较冬闲对照分别提高27.2%,20.5%和18.1%。试验前期（1982-1993）种植绿肥作物各处理之间水稻产量无显著差异,试验开展11年后（1994-2008）种植紫云英处理水稻产量显著高于油菜和黑麦草处理。长期双季稻绿肥轮作土壤有机质随年份显著增加,双季稻紫云英轮作土壤有机质积累速度最快,年增加0.31 g?kg-1,双季稻黑麦草次之,土壤有机质年增加0.28g?kg-1,双季稻油菜轮作土壤有机质年增加0.26g?kg-1。种植绿肥作物紫云英稻田土壤活性有机质显著高于其它处理。种植绿肥作物各处理土壤有机碳、全氮、土壤微生物量碳和土壤微生物量氮含量均显著高于冬闲对照。其中黑麦草和紫云英处理土壤微生物量碳含量及微生物熵显著高于油菜和冬闲对照处理。在湘南红壤丘陵双季稻区,种植绿肥作物对提高水稻产量、增加土壤有机质、提高土壤有机质活性具有重要意义,绿肥选择上以紫云英对水稻产量和稻田土壤培肥综合效果最好。     

Phosphoenolpyruvate carboxylase activity,fixation of14C in amino acids and nitrogen transport in stem nodules ofSesbania rostrata

Thein vivo ¹⁴CO₂ fixation assay and xylem sap analysis showed that inSesbania rostrata the transport of fixed nitrogen from stem nodules was in the amide form. The majority of nitrogen was transported as asparagine. The close relationship between nodule phosphoenolpyruvate carboxylase and nitrogenase activities suggested that nodule CO₂ fixation contributed directly to nitrogen assimilation in stem nodules ofS. rostrata.     

Sequential analysis of nuclei transformation in stem nodulation sites ofSesbania rostrata Bbem (Leguminosae) during infection by specificrhizobium

This paper is a sequential analysis of qualitative and quantitative nuclear evolution inSesbania rostrata (Leguminosae) stem nodules. Before infection, the nuclei of the root primordia (nodulation site) cells show a 2G level of DNA. Immediately upon infection, the cells cease their mitotic activity and the nuclei begin synthesizing DNA up to a 32C level after the onset of the infection. The increase in the diameter of the nuclei of the infected cells is concomitant with the rise in the level of DKA. In the final phase of the evolution of these nodules, the nuclei of the infected cells undergo degenerative changes.     

Application of a green manure and green manure composted with beet vinasse on soil restoration: effects on soil properties

Beet vinasse (BV), a green manure constituted by Trifolium pratense L. uncomposted (TP) and composted with beet vinasse (at 1:1 rate, (TP+BV)1, and 2:1 rate, (TP+BV)2) at 10t organic matter ha(-1) rate were applied during a period of four years for purpose of restoration of a Xelloric Calciorthid located near Seville (Guadalquivir Valley, Andalusia, Spain). The effect on the plant cover, soil physical (structural stability and bulk density), chemical (exchangeable sodium percentage), and biological properties (microbial biomass, soil respiration and enzymatic activities such as dehydrogenase, urease, beta-glucosidase, phosphatase and arylsulfatase) were determined. The application of BV had a detrimental impact on soil physical (structural stability decreased 16.5% and bulk density increased 18.7% respect to the control soil), chemical (exchangeable sodium percentage increased 87.3% respect to the control soil), and biological properties (microbial biomass, soil respiration, and dehydrogenase, urease, beta-glucosidase, phosphatase and arylsulfatase activities decreased by 53.5%, 24.5%, 27.8%, 15%, 39.7%, 42.7%, and 65.6%, respectively with respect to the control soil), probably because high quantities of monovalent cations (Na principally) were introduced into the soil by the vinasse, thus destabilizing its structure. The application of TP had a positive impact on soil physical (structural stability increased 5.9% and bulk density decreased 6.1% respect to the control soil), and biological properties (microbial biomass, soil respiration, and dehydrogenase, urease, beta-glucosidase, phosphatase and arylsulfatase activities increased by 66.3%, 45.6%, 97.7%, 98.9%, 97.7%, 87.2%, and 89.4%, respectively with respect to the control soil). However, when BV was co-composted with a green manure, principally at a 2:1 rate, the resulting compost had a positive effect on soil physical (structural stability increased 10.5% and bulk density decreased 13.5% respect to the control soil), and biological properties (microbial biomass, soil respiration, and dehydrogenase, urease, beta-glucosidase, phosphatase and arylsulfatase activities increased by 68.9%, 46.2%, 97.5%, 98.4%, 99.1%, 90.5% and 91.6%, respectively with respect to the control soil). After four years, the percentage of plant cover decreased 64.3% in the BV-amended plots respect to the control soil, whereas increased 82.8%, 81.6% and 81% in the (TP+BV)2, (TP+BV)1 and TP treatments, respectively. While the application of BV deteriorates the soil and therefore does not contribute to its restoration, the application of TP, and BV composted with TP protects the soil and will contribute to its restoration.     

抑制剂和猪粪对尿素氮在稻田土壤中转化的影响

为了阐明稻田土壤中尿素在配施抑制剂和猪粪的情况下不同形态氮的响应特征,探究不同管理措施下稻田土壤氮素保持和供给能力。本研究采用¹⁵N标记尿素进行盆栽试验,设置不施肥(CK)、猪粪(M)、尿素(N)、猪粪+尿素(NM)、尿素+抑制剂(NI)和尿素+抑制剂+猪粪(NIM)6个处理。抑制剂选用脲酶抑制剂(PPD+NBPT)和硝化抑制剂(DMPP)组合,测定返青期、分蘖期和成熟期土壤氮库的分配、尿素氮在氮库中的保存及水稻吸氮状况。结果表明: 施用猪粪显著提高了土壤铵态氮、固定态铵含量和微生物生物量氮,提高了分蘖期尿素氮在各氮库中的贮存,显著增加了水稻产量。与N处理相比,添加抑制剂促进了NH₄⁺的矿物固定和微生物对尿素氮的固持;与NM处理相比,施用抑制剂增加了黏土矿物对¹⁵NH₄⁺的固定。通径分析表明,施用猪粪能促进水稻吸收肥料氮,增加水稻产量;添加抑制剂可通过铵的矿物固定将更多的肥料氮暂时储存;NIM能将更多的氮贮存在微生物生物量氮中,至作物生长后期,铵的释放和微生物周转矿化可为水稻提供更多的有效氮源。在我国北方稻田,NM和NIM处理是推荐的施肥方式。     

Sorghum-sudan green manure; Its effect on nursery stock

Summary The use of sorghum-sudan green manure has recently attained popularity among nurserymen because of the assumption that toxic excretions of these hybrids control root-rot fungi. Greenhouse trials of 2-year duration have revealed that green manure of sorghum-sudan inflicts severe damage of tree seedlings, largely by eradication of mycorrhiza-forming fungi. Early plowing under of green manure, periodic watering, and late fall seeding of nursery crop may alleviate phytotoxicity of the sorghum-sudan residues, but the biocidic properties of these plants defeat the primary purpose of using green manure in contemporary nurseries, namely the biodegradation of toxic compounds.Research supported by the College of Agricultural and Life Sciences, University of Wisconsin, Madison, and the Wisconsin Department of Natural Resources.     

Nitrous oxide emission from paddy fields in China

The main research results of nitrous oxide (N₂O) emission from paddy fields in China were summarized. Paddy fields are an important source of N₂O emission. Denitrification process exists not only in the upper flooded cultivated layer in paddy fields but also in the underground saturated soil layer. The cropping system with rice–wheat rotation and the water regime with mid-season aeration (MSA) in paddy fields of China are not only the controlling factors of N₂O emission but also the main factors influencing methane (CH₄) emission. There is a trade-off relationship between N₂O and CH₄ emissions from paddy fields. Straw amendment reduced N₂O emission but promoted CH₄ emission. Therefore, effects of both CH₄ and N₂O emissions from rice fields on the global warming potential (GWP) should be taken into consideration when any mitigation options are to be established.     

The spatial–temporal pattern changes of the red crowned crane (Grus japonensis) population in Zhalong NNR and the related driving forces

Understanding spatio-temporal distribution patterns of a species is essential to successful species and habitat conservation. The fluctuations of the red crowned crane population were studied after collecting the data about breeding red-crown cranes from Zhalong National Natural Reserve (Zhalong NNR) since 1981; and their spatial distribution patterns were also quantified in variant time periods with the method nearest neighbor analysis (NNA); the main factors leading to the dynamics of the bird population were analyzed. The results showed the red-crown crane population had fluctuated dramatically from 1981 to 2005. The number dropped rapidly to the minimum of the bird population to endanger the existence of the population by the year of 2005. And the spatial distribution pattern changed from uniform distribution to aggregated distribution during 1996–2005. These changes reflected that the distributions of habitats had undergone a process of fragmentation, and the area of the suitable habitats suffered such a continuous loss that there were insufficient habitats to sustain the bird population any more. And consequently, the decline of the bird population occurred. The wildfire and the anthropogenic activities were the driving forces which accounted for the degradation of the habitats and hereafter the fluctuations of the red-crown population.     

Long-term partial substitution of chemical fertilizer with green manure regulated organic matter mineralization in paddy soil dominantly by modulating organic carbon quality

Plant and Soil - Plant pathogenic and mycotoxin-producing Fusarium species are globally widespread and lead to large annual yield losses in maize production (ecosystem disservice). Systems with...     

Integrated aquaculture in Chinese lakes and paddy fields

While pond culturing is still the staple of Chinese freshwater fisheries, its extensive development is handicapped by the increasing shortage of land resource for cereal production in face of China’s population growth. Accordingly, people have looked towards the development of aquaculture in lakes (and reservoirs) in the 1970s. This paper reviews the successful integrated measures taken in an experiment for raising fish in Donghu lake (East lake) of Wuhan. By way of (1) stocking the right kinds of fish; (2) producing a large number of sizeable fingerlings; (3) improving fish screens; (4) controlling predatory fish; and (5) applying the ‘driving and concentrating’ bulk harvesting fishing method, fish production of the lake has increased steadily from 180 t in 1971 to 800 t in 1978, and then to 1840 t in 1995, all in an area of 1500 ha, and all without any supplementary feeding. Integrated aquaculture in paddy fields, known to be beneficial to both rice and fish production, has been regaining momentum in recent years. The paper summarizes its underlying principle, its benefits—economical, social and ecological—and the prospect of its development in China.     

中国南方集约多熟稻田保护性耕作制度

总结了南方集约多熟农区稻田耕作制度的发展和演变过程,分析了南方集约多熟稻田保护性耕作制的技术特征、模式和研究进展。认为中国南方稻区已形成一系列突破性保护性耕作关键技术,并取得了显著的生态、经济和社会效益,为南方集约多熟稻区的粮食生产和生态环境保护提供了有益的途径;指出了研究和推广中存在的不足,提出在今后南方集约多熟稻区保护性耕作的发展过程中,要继续加强区域布局、技术机理和生态经济评价方面的研究,进一步规范模式和技术集成,为制定保护性耕作技术生态补偿政策提供科学依据。     

稻田生态系统中丛枝菌根真菌的研究进展

水稻是世界上近一半人口的主粮作物,也被认为是研究丛枝菌根真菌(arbuscular mycorrhizal fungi, AMF)与非豆科植物共生的模式寄主植物。由于研究手段的限制,长期以来对稻田AMF多样性和生态功能的认识不够深入。近10年来,随着高通量测序技术的发展,越来越多的研究表明,AMF在稻田生态系统中普遍存在。新技术的发展极大地推动了稻田生态系统中AMF生态功能及其与水稻互作的研究。本文综述了稻田生态系统丛枝菌根(arbuscular mycorrhizal, AM)共生体的建立、AMF的多样性及其影响因素、AMF的生态功能、AMF在水稻栽培中的潜在应用等,并对未来AMF与水稻研究进行了展望。研究表明,AM共生体的建立依赖AMF和水稻间一系列复杂的信号识别、交换和传导机制;相较于稻田湿地环境,旱作环境水稻根中AMF的定殖率更高,而且受寄主植物、环境因子和栽培管理措施等因素影响;AMF在调控水稻生长、营养吸收、抵御环境胁迫、降低稻田甲烷(CH4)和氧化亚氮(N2O)排放等方面发挥着重要功能;AMF与其他微生物联合作用可以更好地帮助水稻吸收养分和抵御环境胁迫。基于稻田生态系统A...     

Influence of rice cultivar on methane emission from paddy fields

Influence of rice cultivars on CH₄ emissions from a paddy field was studied using four Japonica types, two Indica types, and two Japonica/Indica F₁ hybrids. In addition, the suppression of CH₄ emission by interrupting irrigation at the flowering stage was investigated. Patterns of seasonal variation in CH₄ emission rates were similar among the eight cultivars. Two of the Japonica types showed the maximum and minimum CH₄ emissions among the cultivars investigated. Neither the number of tillers, shoot length, shoot weight, and root weight correlated with the CH₄ emission rates at the tillering and reproductive growth stages. Following temporary interruption of irrigation at the flowering stage, CH₄ emission rates decreased drastically and remained at very low levels until the harvesting stage, indicating its great effectiveness for the suppression of CH₄ emission from rice paddies.