Leguminous Green Manure Crops Research Articles

Enhancing Seed Yield of Daincha (Sesbania aculeata L.) New Variety TRY1 Through Optimum Spacing and Nutrient Management

Background: Increasing demand for leguminous green manure crop daincha seed is being noticed throughout the country mainly to restore the soil fertility. For maximizing seed production of newly released daincha variety, an optimum plant density per unit area and fertilizer application are an important management tool. The study was conducted to optimize the plant spacing and fertilizer dose for achieving higher seed yield of daincha variety TRY 1. Methods: Field experiments were conducted during Summer and Kharif 2023 to study the effect of different spacing and fertilizer doses on growth, yield and economics of new daincha variety TRY1. The treatments consisted of five different spacing (S1-75×30 cm, S2-60×30 cm, S3-75×45cm, S4-60×45 cm and S5-90×30 cm) in main plots and three fertilizer levels (F1-12.5:25:12.5 kg N, P2O5, K2O ha-1, F2-18.75:37.5:18.75 kg N, P2O5, K2O ha-1, F3-25:50:25 kg N, P2O5, K2O ha-1 and control) in sub plots were tested. The treatments were replicated thrice in split plot design. Result: Growing of daincha variety TRY 1 at 60×45 cm spacing produced significantly taller plants (223 cm), more number of branches per plant (15.9) and dry matter production (1766 kg ha-1), yield parameters viz., higher mean number of pods per plant (114), pod length (22.4 cm) and seeds per pod (36.7), seed yield (567 kg ha-1), mean net returns (Rs.24512 ha-1) and benefit cost ratio (2.36) than other spacing. Application of 25:50:25 kg N, P2O5, K2O ha-1 recorded significantly mean taller plants (217 cm), more number of branches per plant (19.3), dry matter production (1831 kg ha-1), nodules/plant (40.7), more number of pods /plant (121), pod length (23.7 cm) and seeds per pod (37.8), seed yield (572 kg ha-1), net returns (Rs.23369 ha-1) and benefit cost ratio (2.20) over other fertilizer doses. Thus, the optimum spacing of 60×45 cm and fertilizer dose of 25: 50:25 kg N, P2O5, K2O ha-1 could be recommended for getting higher growth, yield parameters, seed yield, net returns and benefit cost ratio of newly released daincha variety TRY 1.

Green manure provides growth benefits for soil mesofauna by promoting soil fertility in agroecosystems

The cultivation of leguminous green manure (LGM) crops in place of bare fallow in summer enhances soil fertility, which can positively impact soil life in the agroecosystem. An improvement in soil life, in turn, can promote soil fertility and agricultural sustainability. Based on an ongoing field trial in the Loess Plateau, China, we investigated the long-term effects of LGM crops and nitrogen (N) fertilization on soil mesofaunal community and analyzed the interrelationships among the various mesofaunal groups and soil fertility under dryland conditions. The results showed that the long-term growth of the LGM crops significantly increased the soil fertility and the abundance, richness, and diversity of the soil mesofaunal community compared to the fallow system. A total of 14 mesofaunal groups were identified only in the LGM system, mainly due to the high root biomass of the LGM crops. Among the three tested LGM crops, soybean and Huai bean performed better than mung bean in providing growth benefits and stable abiotic environments for the soil mesofaunal community. In addition, the long-term application of N fertilizer had an overall negative effect on the soil mesofaunal community under dryland conditions. Moreover, the abundance, richness, and diversity of the soil mesofaunal community were strongly correlated with soil fertility indicators. Hence, the analysis of the soil mesofaunal community can be used as a bioindicator of soil fertility in agroecosystems. The long-term growth of the LGM crops instead of bare fallow efficiently built a more sustainable and fertile soil in the agricultural ecosystem, thus providing a theoretical basis and guiding field management strategies for the development of sustainable agriculture in local and other similar dryland regions.

Symbiotic nitrogen fixation enhanced crop production and mitigated nitrous oxide emissions from paddy crops

Feeding a growing population and preventing dangerous climate change are two challenges facing humanity. Biological nitrogen (N) fixation is considered a sustainable production measure that helps maintain crop production and mitigate climate change by supplementing alternative N nutrients. However, the simultaneous impacts of symbiotic N fixation (SNF) by leguminous green manure crops on rice crop production and nitrous oxide (N2O) emissions remain poorly understood. Here, a field experiment of two annual rotation cycles was conducted to monitor rice yield and the N2O emissions under rice (Oryza sativa subsp. japonica Kato.)-wheat (Triticum aestivum L.) (RW) and rice-hairy vetch (Vicia villosa Roth.) (RV) cropping systems at three N input rates (0 (N0), 50 (N1) and 100 (N2) kg ha−1) for the upland crops and 200 kg ha−1 for the rice crop. Growing hairy vetch introduced a significant amount of N as SNF to the agroecosystem, ranging from 123 to 182 kg ha−1. Compared to the treatments without N for the RV system, the N1 and N2 treatments significantly increased the amount of SNF by 44–47% and 19%− 24%, respectively. The cumulative N2O emissions from SNF ranged from 0.28–0.65 kg ha−1, with the N2O emission factor from SNF (EFSNF) ranging from 0.18%− 0.52% for the RV system. The RV system significantly decreased the N2O emission factor from the total N input (EFTN) by an average of 10.0% compared with the RW system. The RV-N1 treatment produced an obviously lower EFTN, averaging 0.37%, than the other treatments receiving N applications. Compared to the RW system, the RV system slightly increased rice yield by an average of 3.5%. Therefore, the most appropriate N application rate was 50 kg ha−1 for the leguminous crop, and SNF of leguminous green manure could serve as complementary to mineral N fertilizers for reducing N2O emissions while improving soil quality and rice yield in paddy field.

Decomposition and nutrient release pattern of three potential leguminous green manure crops of Mizoram

Aim: The experiment was carried out to understand the decomposition and nutrient release dynamics (N, P and K) of Crotolaria micans Link, Aeschynomene indica L. and Calopogonium mucunoides Desv. using the litter bag technique. Methodology: The species were harvested at their peak vegetative stage and air-dried for a week. Air-dried samples (10 g) were placed in 20 cm X 20 cm nylon mesh bags and buried at 10 cm soil depth in an experimental plot of 1.5 m X 1.5 m prepared for each species. The bags were retrieved monthly, and the mass and nutrient loss were determined. Results: C. micans had the highest decay rate (7.67 k per year), followed by C. mucunoides (7.15 k per year) and A. indica (5.50 k per year). During the decomposition period, K release was the fastest. The decay rate was negatively correlated with initial lignin, total phenol and lignin/N of which the total phenol (R2 = 0.956) and lignin/N ratio (R2 = 0.832) had the most significant influence on decomposition. Interpretation: The study reveals that the species can be effectively utilized as a soil nutrient input source of which C. micans seems to be the most potential species to be further researched and developed as a green manuring crop. Key words: Decomposition, Decay rate, Green manure, Legume, Nutrient release

Nitrogen Fate of Chemical Fertilizer and Green Manure-Wheat Rotation Using 15N Tracer Technique

To investigate the accumulation, distribution, and translocation of nitrogen (N) from chemical fertilizers and green manure in wheat plants, we conducted an experiment using leguminous green manure crop hairy vetch and wheat as test materials. During the anthesis and maturity stages of wheat, the 15N enrichment and Nitrogen content of wheat plant samples were determined in different organs, and 15N enrichment and nitrogen content of soil samples were measured at maturity. The accumulation and distribution characteristics of nitrogen from different sources during the wheat growth stages were investigated to explore the impacts of green manure and chemical fertilizers on wheat growth and nitrogen uptake. The results showed that nitrogen from chemical fertilizers in the soil-plant system exhibited the following pattern: plant absorption > soil residue > loss, while nitrogen from green manure showed: soil residue > loss > plant absorption. Wheat had higher absorption of nitrogen from chemical fertilizers compared to green manure. The absorption of nitrogen from chemical fertilizers by wheat ranged from 46.00% to 54.08%, while the absorption of nitrogen from green manure ranged from 20.71% to 28.21%. The residual nitrogen from green manure in the soil (38.47% to 58.22%) was higher than that from chemical fertilizers (31.44% to 40.69%), and the nitrogen loss from green manure (21.07% to 33.31%) was higher than that from chemical fertilizers (5.22% to 22.56%). Supply of nitrogen from the two sources could coordinate the distribution of nitrogen in various organs and increase the proportion of nitrogen allocation in grains. This was beneficial for facilitating nutrient transfer to reproductive organs.

Effects of green manure intercropping on soil nutrient content and bacterial community structure in litchi orchards in China

Green manure intercropping is an agronomic management practice that effectively increases soil nutrients in understory and reduces weed population. However, the influence of different green manures on soil properties and soil bacterial community in litchi orchards in the tropical regions of China remains largely unknown. Here, we examined the effect of intercropping three leguminous green manure crops in litchi orchards of Hainan Province. No intercropping was used as the control. Different green manures increased the contents of different soil nutrients. For example, Desmodium ovalifolium increased the total nitrogen content by 7.93%; Grona heterocarpos increased the ammonium nitrogen content by 558.85%; and Stylosanthes guianensis increased the available phosphorus content by 1207.34%. However, intercropping with D. ovalifoliu and S. guianensis reduced the content of available potassium by 47.29% and 58.48%, respectively. The intercropping of green manure increased the abundance of several microbial genera, including Bradyrhizobium, Serratia, and Bacillus, which are known to facilitate soil nitrogen accumulation, plant growth, and phosphorus dissolution. Compared with no intercropping, the three intercropping treatments significantly improved the contents of soil ammonium nitrogen and soil available phosphorus in the litchi orchard. Therefore, intercropping with green manure crops in litchi orchards is an effective management measure; however, the choice of the green manure crop should be based on the soil conditions of litchi orchards.

Effect of leguminous green manure crops on white cabbage in organic vegetable production in southwestern Germany

ISHS III International Organic Fruit Symposium and I International Organic Vegetable Symposium Effect of leguminous green manure crops on white cabbage in organic vegetable production in southwestern Germany

Transfer characteristics of nitrogen fixed by leguminous green manure crops when intercropped with maize in northwestern China

To ascertain the possibility of cultivating maize using biological nitrogen fixation (BNF) by leguminous green manure crops in maize/leguminous green manure intercropping systems, BNF and nitrogen (N) transfer were studied in Xining and Wuwei, two typical northwestern Chinese cities. The experimental treatments included monocultured maize, monocultured green manures (hairy vetch and common vetch), and their intercropping systems. The proportions of N derived from the atmosphere (%Ndfa) in intercropping systems were not significantly different from that in monocultured green manure systems at either experimental site, except for that in hairy vetch (HV) in Xining. The amount of N derived from the atmosphere (Ndfa) of common vetch (CV) significantly decreased from 1.16 and 1.10 g/pot in monoculture to 0.77 and 0.55 g/pot when intercropped with maize, in Xining and Wuwei, respectively, and the Ndfa of HV when intercropped significantly decreased from 1.02 to 0.48 g/pot in Xining. In the intercropping systems in Xining and Wuwei, the amounts of N transferred (Ntransfer) from CV to maize were 21.54 and 26.81 mg/pot, accounting for 32.9 and 5.9% respectively of the N accumulation in maize, and the values of Ntransfer from HV to maize were 39.61 and 46.22 mg/pot, accounting for 37.0 and 23.3%, respectively, of the N accumulation in maize. Path analysis showed that soil nutrient and green manure biomass were mainly related to Ndfa, and that δ15N had a primary relationship with Ntransfer. We found that 5.9–37.0% of N accumulation in maize was transferred from green manures, and that the N transfer ability to maize of HV was higher than that of CV. In conclusion, intercropping with leguminous green manures provided a feasible way for maize to effectively utilize biologically fixed N.

Basmati Rice Quality Enhancement by Zinc Fertilization and Green Manuring on a Sub-tropical Inceptisol in Indo-Gangetic Plains of India

Basmati (aromatic) rice is premier rice grown in north-western India and Pakistan. This rice is preferred for their long and slender kernels which expand 3-4 times in length and remain fluffy and are well known all over the world, especially in the Middle East and South Asia for their long fluffy grains on cooking. Paddy soils are usually deficient in organic matter because of high temperature and moisture, which causes rapid decomposition of organic matter. The importance of leguminous green manure crops in improving soil fertility, and soil physical properties received increasing attention. Also, the zinc (Zn) deficiency in soils is prevalent worldwide, especially in high pH calcareous soils. No reports were available on combining green manuring crops and Zn fertilization on productivity, Zn content and kernel quality of Basmati rice. Therefore, the current investigation was undertaken to quantify the combined effects of summer green manuring crops and zinc fertilization on productivity, Zn content and kernel quality of Basmati rice in summer green manuring-Basmati rice cropping system. A field study was therefore conducted for two years (2009 and 2010) on a sandy clay-loam soil (typic Ustochrept) at the research farm of the ICAR-Indian Agricultural Research Institute, New Delhi, India. The experiments were conducted in split plot design, keeping three green manuring crops viz. Sesbania aculeata (Dhaincha), Crotalaria juncea (Sunhemp), and Vigna unguiculata (Cowpea) and one summer fallow treatment as main-plot treatments and six Zn sources viz. control (no Zn application), ZnSO4∙7H2O (21% Zn), ZnSO4∙H2O (33% Zn), ZnO (82% Zn), ZnSO4∙7H2O + ZnO (50% + 50%) and EDTA-chelated Zn (12% Zn) in sub-plots and was replicated thrice. The experiments in both the years were conducted with a fixed lay-out plan on the same site. The results showed that incorporation of green manures along with zinc (Zn) fertilization increased grain and straw yield, enhanced Zn concentrations and improved the kernel quality before and after cooking in Basmati rice ‘Pusa Basmati 1’. The application of EDTA-chelated Zn (12% Zn) was the best in terms of grain and straw yield and Zn concentrations in grain and straw and kernel quality before and after cooking Basmati rice. Application of ZnSO4∙7H2O (21% Zn) was the second-best treatment followed by ZnSO4∙H2O (33% Zn) and ZnSO4∙7H2O + ZnO (50% + 50%). Application of ZnO (82% Zn) had least effect in increasing the studied parameters. The lowest values were observed with control (no Zn application). Among the summer green manuring crops, incorporation of Sesbania aculeata (Dhaincha) was found to be the best over Crotalaria juncea (Sunhemp), Vigna unguiculata (Cowpea) and summer fallow in terms of grain and straw yield, Zn concentrations in grain and straw and kernel quality before and after cooking in Basmati rice. Zn fertilization with EDTA-chelated Zn (12% Zn) lead to 25.91 and 21.26% higher grain yield; 60.66 and 82.14% Zn-denser grains; with 13.33 and 10.92% increase in head rice recovery in Basmati rice over control (no Zn application) during 2009 and 2010, respectively.

Legacy effects of leguminous green manure crops on the weed seed bank in organic crop rotations

Legacy effects of leguminous green manure crops on the weed seed bank in organic crop rotations

Legacy effects of leguminous green manure crops on the weed seed bank in organic crop rotations

Leguminous green manure crops are important for accumulating nitrogen by means of biological nitrogen fixation and for building up soil fertility in organic arable cropping systems. Whole-year green manure crops are also known to deplete the soil weed seed bank, e.g. by decaying and predation, but there is uncertainty about the magnitude of the legacy effect after termination of the green manure crop. This study sampled soil for weed seed bank assessment upon termination of a two-year leguminous green manure crop and then one, two and three years afterwards. The samples were taken from two five-year crop rotations (2011–2015) in a long-term organic crop rotation experiment in Denmark. One rotation (O2) had a two-year green manure crop followed by three years of annual cash crops, and the other rotation (O4) consisted only of annual cash crops, with four crop sequences in both rotations represented every year. In general, the weed seed bank of rotation O2 was 54 % lower than O4, with 5475 seeds m−2versus 11,967 seeds m−2. Similarly the aboveground amount of weed biomass in O2 was lower than in O4 over the course of the five years. The legacy effect of the green manure crop showed a negative exponential rise in weed seed numbers with the increase in years after termination of the green manure crop. A biennial leguminous green manure crop can mitigate weed problems in organic annual crops. This effect adds to the benefits of including nitrogen fixing leys in crop rotations with limited access to animal manures.

Improving soil aggregation, aggregate‐associated C and N, and enzyme activities by green manure crops in the Loess Plateau of China

AbstractGreen manure and fertilization practices have substantial impacts on soil chemical and biological properties over time. A field experiment was conducted on Cumulic Haplustoll to investigate the effects of leguminous green manure (LGM) crops and nitrogen (N) fertilizer on dry‐stable soil aggregate distributions and stability, the concentrations of organic carbon (OC) and N in the bulk soil and separated aggregate fractions, and soil enzyme activities in dry croplands on the Loess Plateau of China. Species tested as LGM crops were Huai bean (Glycine ussuriensis Regel et Maack.), soybean (G. max (L.) Merr.) and mung bean (Phaseolus radiatus L.). Two rates of N fertilizer (0 and 162 kg N ha−1) applied to winter wheat sown after LGM was incorporated into surface soil. Results showed that the inclusion of LGM crops for 6 years significantly increased the total nitrogen (TN), soil organic carbon (SOC), aggregate‐associated N and OC concentrations, enhanced the values of aggregate content with >0.25 mm size (R0.25) and mean weight diameter (MWD), and boosted soil enzyme (invertase, urease, dehydrogenase and aryl‐sulfatase) activities at the 0–20‐cm depth compared to the bare fallow system under dryland conditions. The long‐term application of N fertilizer substantially increased the proportion of macroaggregates (>5.0 mm), MWD and N contents in the 0.25–5‐mm size aggregates, and promoted the relative activities of invertase, alkaline phosphatase, dehydrogenase and aryl‐sulphatase, but decreased the urease activity. The correlations among macroaggregate fractions and soil chemical properties, aggregate stability and enzyme activities were significant and positive; however, the correlations between small aggregate fractions (<2 mm) and corresponding parameters were negative, or there were no correlations. Overall, combining green manuring practices with suitable N fertilizer application should be recommended to improve the soil quality in dryland regions similar to the Loess Plateau of China.Highlights Green manure crops significantly increased soil enzyme activities, SOC and total N contents. Green manure crops increased macroaggregate (>5 mm) formation and stability. Application of N fertilizer significantly increased the proportions and stability of macroaggregates. Green manure crops along with N fertilizer helped to build better soil quality in a dry loess cropland.

중부지역 답리작에서 두과 및 화본과 녹비작물의 재배방법에 따른 biomass, 질소 함량이 벼 수량에 미치는 영향

The cultivation methods are important for determining crop yield of green manure. The effect of cultivation methods of green manure crops (GMC) on biomass and rice yield was investigated. This experiment was conducted at Sinheung series (fine loamy, mixed, nonacid, mesic family of Fluvaquentic Endoaquepts from Oct. 2007 to Oct. 2008 at the National Institute of Crop Science (NICS), RDA, Suwon, Gyeonggi province, Korea. Seven GMC (hairy vetch, barley, Chinese milk vetch, rye, crimson clover, oats, rattail fescue) were cultivated and incorporated on paddy soil by broadcasting before rice harvesting (BBRH) and partial tillage seeding (PTS). Among the three leguminous GMC, the biomass and N production were the highest at the hairy vetch of PTS. Among the four gramineae GMC, the biomass and N production tended to be higher in the rye of BBRH and barley of PTS. The C/N ratio (56.5～74.2) of rye was high compared with hairy vetch (14.1). Among the GMC, the incorporation of hairy vetch increased NH4-N contents in rice paddy soil at 14 and 42 days after transplanting. These results showed that hairy vetch had no significant to rice yield compared with conventional fertilization. Therefore, hairy vetch seems to be the most efficient green manure crop as an alternatives to chemical N fertilizer in the central regions of Korea.

The effects of pure and undersowing green manures on yields of succeeding spring cereals

A field experiment was conducted in 2004–2006 to investigate the effect of green manure treatments on the yield of oats and spring barley. In the experiment, different green manure crops with undersowing and pure sowing were compared for amounts of N, C, and organic matter driven into soil and their effect on cereal yield. The spring barley field had a total of 41.7–62.4 kg N ha−1 and 1.75–2.81 Mg C ha−1 added to the soil with straw, weed, and roots, depending on the level of fertilisation; with red clover, and both common and hybrid lucerne undersowing, with barley straw and roots, the values were 3.45–3.96 Mg C ha−1 and 139.9–184.9 kg N ha−1. Pure sowings of these three leguminous green manure crops had total applications of 3.37–4.14 Mg C ha−1 and 219.7–236.8 kg N ha−1. The mixed and pure sowing of bird's-foot trefoil provided considerably less nitrogen and carbon to the soil with the biomass than with the other leguminous crops. Application of biomass with a high C/N ratio reduced the yield of the succeeding spring cereals. Of the green manures, the most effective were red clover and both common and hybrid lucerne, either as undersowing or as pure sowing. Undersowings with barley significantly increased the N supply for the succeeding crop without yield loss of the main crop compared with the unfertilised variant. Compared with ploughing-in of green manure in autumn, spring ploughing gave a 0.2–0.57 Mg ha−1 larger grain yield.

マメ科緑肥作物のダイズシストセンチュウ密度低減効果およびキタネグサレセンチュウに及ぼす影響

マメ科緑肥作物のダイズシストセンチュウ密度低減効果およびキタネグサレセンチュウに及ぼす影響

Biological N 2 fixation and residual N benefit of pre-rice leguminous crops and green manures

Rice yields in soils of low soil organic matter may benefit from preceding leguminous green manure crops. A pre-rice crop experiment, including groundnut ( Arachis hypogaea), mung-bean (Vigna radiata), Sesbania (Sesbania rostrata), and a mixture of Sesbania and multipurpose cowpea ( Vigna unguiculata) was conducted on a characteristic sandy soil of North East Thailand. The Sesbania-cowpea intercrop gave a similar total plant biomass as the Sesbania green manure alone (7 t ha −1) but with the advantage to yield an edible product. The direct economic yield of cowpea was 1.3 t ha −1 green beans and greater than that achieved with groundnut or mungbean. The Sesbania-cowpea combination also proved to enhance rice yields by 0.8 t ha −1. The benefits in rice production were similar to the Sesbania green manure alone but surpassed the yields with the other grain crops or urea fertilizer of 30–60 kg N ha −1. Sesbania dry matter production increased with increasing planting density. The resulting variation in plant quality, e.g. lignin, however, was low. Rice responses to treatments were more related to the total residue N yields than to changes in plant quality. Apart from mungbean (25%) the pre-rice leguminous crops were able to obtain a considerable (>39%) proportion of their N from N2 fixation. The green manure Sesbania however fixed a larger proportion (79–89%) of its N than the grain crops (25–62%). This led not only to high amounts of N 2 fixed by Sesbania but together with a N harvest index of zero yielded a large systems N benefit. With grain legumes this benefit was moderated by the N export in harvestable products. In the case of mungbean this may even result in effective soil N mining. Residue N use efficiency varied between 19–29% and was similar to that obtained from a single application of chemical N fertilizer (17–28%). For the farmer the Sesbania-cowpea intercrop option seems thus the most promising one not only regarding rice yield benefits but also in terms of soil fertility enhancement and generation of edible products.

Dry matter and nitrogen accumulation by three leguminous green manure species and the yield of a following wheat crop in an organic production system

Organic farming systems often include livestock to use the leguminous forages which supply nitrogen (N) to the grain crops in the rotation. An alternative approach (especially relevant to farms with ‘set-aside’) may be to manage leguminous green manure crops by repeatedly cutting and mulching them directly in the field. An experiment (carried out on an organic farm in the UK) compared the dry matter and N accumulation of legumes grown for periods of between 6 months and 2 years, compared with a non-leguminous rye-grass ( Lolium spp.) control. The performance of a subsequent wheat ( Triticum aestivum L.) crop was also measured. Red clover ( Trifolium pratense L.), white clover ( Trifolium repens L.) and trefoil ( Medicago lupulina L.) green manures and the rye-grass control were cut to maintain a height of no more than 30–40 cm, and the cut material was left on the soil surface (‘mulching’). Of the legumes, white clover accumulated the most dry matter (12.2 t DM ha −1 year −1) and red clover the most N above ground (371 kg N ha −1 year −1) over a 1 year period of green manuring. Both these species accumulated significantly more dry matter and N than trefoil and ryegrass. Yields of following wheat crops varied considerably. Spring wheat (grown after 6 and 18 months of green manuring) did not yield at a commercial level due to poor establishment. Winter wheat generally yielded well following 1 year of green manuring with red (6.0 t ha −1) and white clover (5.2 t ha −1) and significantly more than following trefoil and the nil-legume ryegrass control (3.3 t ha −1 and 2.1 t ha −1, respectively). The results suggest that red clover is the optimum species for use as green manure. This is relevant in the context of set-aside management. There was no indication that winter wheat yield was improved following a second year of green manuring with either red or white clover. Approximately one third of the total N accumulated by red clover above-ground was lost by leaching (measured using porous ceramic cup samplers) following cultivation of the 1-year green manure in September prior to establishing a winter wheat crop. Delaying cultivation until the spring substantially reduced leaching due to uncultivated soil over winter. The environmental risks (and agronomic benefits) associated with farming systems relying on natural N fixation and soil microbial activity should be more fully evaluated.

熱帯マメ科緑肥作物による低湿重粘土輪換田の土壌改良 第１報 セスバニア，クロタラリア： その生育特性と土壌物理性改善効果

1) We investigated the possibility to utilize troprical leguminous green manure crops for improvement of soil physical properties and management of soil fertility in ill-drained clayey paddy fields in Hokuriku district.2) We carried out this experiment in 1988 at the field of Hokuriku National Agricultural Experiment Station. The crops used were Sesbania cannabia, S. rostrata and Crotalaria juncea. We mesured productivity of dry matter, development of root-systems, and degree of drying and oxidization of soil to estimate the utility value.3) The dry matter yields of S. cannabia, S. rostrata and C. juncea were 1.4, 1.2 and 0.9kg/m2 respectively. The cracks were formed and the drying and the oxidization were activated in the lower layer of the soil by the development of the root systems. The position grey soil appeared in the soil was lowered till 33-45cm, and the depth of root of S. cannabia, s. rostrata and C. juncea were 80, 62 and 52cm respectively.4) The leguminous bacteria of S. cannabia, S. rostrata and C. juncea was Rhizobium. Azorhizobium and Bradyrhizobium respectively. Azorhizobium which forms the nodules not only on root, but on stem of S. rostrata, was identified in fields for the first time in Japan.

The Use ofTrifolium repens, Trifolium subterraneumandMedicago lupulinaas Overwintering Leguminous Green Manures

ABSTRACT A field trial was carried out to compare the performance of three species of overwintering leguminous green manure crops with a fallow. White clover produced the greatest amounts of nitrogen (45–60 kg/ha). Subterranean clover produced the greatest amount of dry matter (1600 kg/ha). Trefoil had the deepest root system but did not nodulate. The concentrations of soil nitrate were significantly higher under the white clover sward than under the other legume and fallow swards.

Soil microbial biomass and selected soil enzyme activities: Effect of fertilization and cropping practices

Selected microbiological properties of soils receiving different fertilizer management regimes were studied from adjoining wheat farms in the highly productive Palouse region of eastern Washington. Since 1909, the only N input to the soil of Farm Management System 1 has been through leguminous green manure crops consisting most recently of Austrian winter peas ( Pisum sativum ssp. arvense L., Poir), plus native soil fertility for N and all other plant nutrients. The soil of Farm Management System 2 received regular applications of anhydrous ammonia, P and S at recommended rates for the last 30 yr. There were no differences in numbers of soil microorganisms as determined by plate counts; however, soil from management system 1 had significantly higher levels of urease, phosphatase and dehydrogenase at all three samplings and significantly higher soil microbial biomass at the first two samplings. The data indicate that management system 1 soil had a larger and more active soil microflora.