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Background: Organic vegetable production has a demand for alternative fertilizers to replace fertilizers from sources that are not organic, that is, typically animal‐based ones from conventional farming. Aims: The aim of this study was to develop production strategies of plant‐based fertilizers to maximize cumulative nitrogen (N) production (equal to N yield by green manure crops), while maintaining a low carbon‐to‐nitrogen (C:N) ratio, and to test the fertilizer value in organic vegetable production. Methods: The plant‐based fertilizers consisted of the perennial green manure crops—alfalfa, white clover, red clover, and a mixture of red clover and ryegrass—and the annual green‐manure crops—broad bean, lupine, and pea. The crops were cut several times at different developmental stages. The harvested crops were used fresh or pelleted as fertilizers for field‐grown white cabbage and leek. The fertilizer value was tested with respect to biomass, N offtake, N recovery, and soil mineral N (Nmin). Poultry manure and an unfertilized treatment were used as controls. Results: The cumulative N production of the perennial green manure crops ranged from 300 to 640 kg N ha–1 year–1 when cut two to five times. The highest productions occurred at early and intermediate developmental stages, when cut three to four times. Annual green manure crops produced 110–320 kg N ha–1 year–1, since repeated cutting was restricted. The C:N ratio of the green manure crops was 8.5–20.5, and increased with developmental stage. The fertilizer value of green manure, as measured in white cabbage and leek, was comparable to animal‐based manure on the condition that the C:N ratio was low (<18). N recovery was 20%–49% for green manure and 29%–42% for poultry manure. A positive correlation was detected between soil Nmin and vegetable N offtake shortly after incorporating the green manure crops, indicating synchrony between N release and crop demand. Conclusions: Plant‐based fertilizers represent highly productive and efficient fertilizers that can substitute conventional animal‐based fertilizers in organic vegetable production. [ABSTRACT FROM AUTHOR]

Widespread use of legume green manures is limited by a lack of reliable varieties that meet the needs of farmers. Improving symbiotic N fixation (SNF) in open‐pollinated legume species poses a challenge because normal methods used for assessing SNF conflict with breeding practices such as seed production and removing low‐quality sires. We investigated methods for measuring symbiotic N fixation that are compatible with breeding practice for two major legume cover crops: hairy vetch (Vicia villosa Roth) and crimson clover (Trifolium incarnatum L.). We collected two nondestructive samples at the early‐flowering stage (Meristem and Wedge) and a sample at seed harvest (Seed). Our objective was to determine which combination of measurements best predicted symbiotic N fixation (% N derived from atmosphere [Ndfa]) and total N content at 50% flowering. Our statistical approach accommodated the problem that target traits and seed measurements cannot be measured in the same individuals. Overall, the Wedge sample provided the best prediction for Ndfa at 50% flowering. The best predictions for total N plant–1 came from combining vigor ratings with aboveground biomass at seed harvest. In addition to specific recommendations for legume cover crop breeding programs, we provide a flexible statistical method for studying relationships between traits that cannot be measured jointly. Core Ideas: Symbiotic N fixation (SNF) was highly variable within two legume species.We identified the best nondestructive methods for predicting farmer‐relevant SNF traits.The best proxy for Ndfa at 50% flowering was 15N in a Wedge sample at early flowering.Total N yield was best predicted by typical breeding indicators of plant size.We present novel tools for analyzing traits that cannot be measured in the same individuals. [ABSTRACT FROM AUTHOR]

Although direct tree seeding may be a potentially useful restoration practice, many biotic and abiotic barriers prevent seedling emergence and early development, reducing its success and applicability. To overcome these barriers, we undertook a field experiment to test the effects of using green manure and hydrogel alone, or in combination, on seedling performances of 14 native tree species that were planted by direct seeding in a deforested tropical seasonal forest area in southern Brazil and to examine how green manure affected the initial weed coverage in the study plots. We evaluated competing vegetation coverage and tree seedling emergence and early development for 2 years after sowing. Weed infestation was significantly higher in the experimental plots with no green manure; however, neither green manure nor hydrogel improved tree seedling emergence and early development at any time of measurement. Our results suggest that the use of green manure and hydrogel alone, or in combination, were not effective in guaranteeing direct seeding success; however, green manure can be an effective method to reduce weed infestation. Direct seeding techniques for tree species still need to be improved in order to restore tropical seasonal forests on a larger scale. [ABSTRACT FROM AUTHOR]

BACKGROUND Driven by environmental concerns, chemical fumigants are no longer allowed in many countries. Therefore, other strategies for reducing fungal inoculum in soils and on crop debris are being explored. In the present study, several Brassicaceae crops were screened for their potential to control Fusarium gramineaum and Fusarium poae mycelial growth in an in vitro inverted Petri dish experiment. Volatile production was measured using gas chromatography‐mass spectrometry headspace analysis. A selection of cultivars from each crop species was further investigated using a pot experiment with maize. RESULTS: Ethiopian mustard (Brassica carinata) and brown mustard (Brassica juncea) released volatile allyl isothiocyanate (AITC) and a higher concentration of AITC was correlated with a better fungal growth reduction in the in vitro screening. Brown mustard cultivar Etamine completely inhibited growth of both Fusarium spp. Pure AITC in a solution with methanol resulted in a sigmoid dose–response curve for both Fusarium spp. tested. Fusarium poae appeared to be more tolerant to AITC than F. graminearum. A pot experiment revealed that the incorporation of brown mustard plant material could alleviate the clear negative effect of F. graminearum infection on maize growth. CONCLUSION: The present study demonstrated the correlation between the fungistatic effect of biofumigation crops on Fusarium spp. and their production of volatile AITC in vitro, without the addition of exogenous enzymes, and confirmed the biofumigation potential of brown mustard in a pot experiment with maize. These results may help farmers when selecting a green manure crop suitable for biofumigation. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The narrow‐leafed lupin, Lupinus angustifolius L., is a grain legume crop, cultivated both as a green manure and as a source of protein for animal feed and human food production. During its domestication process, numerous agronomic traits were improved, however, only two trait‐related genes were identified hitherto, both by linkage mapping. Genome‐wide association studies (GWAS), exploiting genomic sequencing, did not select any novel candidate gene. In the present study, an innovative method of 3′‐end reduced representation transcriptomic profiling, a massive analysis of cDNA ends, has been used for genotyping of 126 L. angustifolius lines surveyed by field phenotyping. Significant genotype × environment interactions were identified for all phenology and yield traits analysed. Principal component analysis of population structure evidenced European domestication bottlenecks, visualized by clustering of breeding materials and cultivars. GWAS provided contribution towards deciphering vernalization pathway in legumes, and, apart from highlighting known domestication loci (Ku/Julius and mol), designated novel candidate genes for L. angustifolius traits. Early phenology was associated with genes from vernalization, cold‐responsiveness and phosphatidylinositol signalling pathways whereas high yield with genes controlling photosynthesis performance and abiotic stress (drought or heat) tolerance. PCR‐based toolbox was developed and validated to enable tracking desired alleles in marker‐assisted selection. Narrow‐leafed lupin was genotyped with an innovative method of transcriptome profiling and phenotyped for phenology, growth and yield traits in field. Early phenology was found associated with genes from cold‐response, vernalization and phosphatidylinositol signalling pathways, whereas high yield with genes running photosystem II and drought or heat stress response. Key loci were supplied with PCR‐based toolbox for marker‐assisted selection. Narrow‐leafed lupin was genotyped with an innovative method of transcriptome profiling and phenotyped for phenology, growth and yield traits in field. Early phenology was found associated with genes from cold‐response, vernalization and phosphatidylinositol signaling pathways, whereas high yield with genes running photosystem II and drought or heat stress response. Key loci were supplied with PCR‐based toolbox for marker‐assisted selection. [ABSTRACT FROM AUTHOR]

Common scab of potato caused by various species in the genus Streptomyces has assumed serious proportions in certain potato‐growing regions of North India. Although it does not have significant effect on tuber yield, it downgrades quality and reduces marketability. Being soil‐borne, this disease is often difficult to manage. Therefore, the present studies were conducted to evaluate different potato‐based crop rotations prevalent in north India as a part of a strategy to manage Streptomyces scabies population in scab sick fields. Our results showed that S. scabies population in soil can be effectively reduced either by keeping the field fallow after potato or by including mungbean or sunhemp as green manure, in a single year cropping sequence over a period of four years. Three crop rotations, viz. fallow–rice–potato, mungbean–rice–potato and sunhemp–rice–potato, showed maximum decrease in the population of S. scabies in soil resulting in reduced scab severity. The mungbean‐ and sunhemp‐based crop rotations also enhanced rhizospheric soil microflora especially fluorescent pseudomonads and Trichoderma spp. [ABSTRACT FROM AUTHOR]

Rye is a multi‐purpose cereal crop grown in Central and Eastern Europe as well as in Western Canada. Fusarium head blight (FHB) is one of the diseases that have a severe negative impact on rye, but knowledge about FHB resistance at the genomic level is totally missing in rye. The objective of this study was to elucidate the genetic architecture of FHB resistance in winter rye using genome‐wide association (GWA) mapping complemented by genomic prediction (GP) in comparison with marker‐assisted selection (MAS). Additionally, plant height and heading stage were analysed. A panel of 465 S1‐inbred lines of winter rye was phenotyped in three environments (location–year combinations) for FHB resistance by inoculation with Fusarium culmorum and genotyped with a 15k SNP array. Significant genotypic variation and high heritabilities were found for FHB resistance, heading stage and plant height. FHB did not correlate with heading stage, but was moderately correlated with plant height (r = −.52, p <.001) caused by some susceptible short inbred lines. The GWA scan identified 15 QTL for FHB resistance that jointly explained 74% of the genotypic variance. In addition, we detected 11 QTL for heading stage and 8 QTL for plant height, explaining 26% and 14% of the genotypic variance, respectively. A genome‐wide prediction approach resulted in 44% higher prediction abilities than marker‐assisted selection for FHB resistance. In conclusion, genomic approaches appear promising to improve and accelerate breeding for complex traits in winter rye. [ABSTRACT FROM AUTHOR]

The application of organic materials to soil can recycle nutrients and increase organic matter in agricultural lands. Digestate can be used as a nutrient source for crop production but it has also been shown to stimulate greenhouse gas (GHG) emissions from amended soils. While edaphic factors, such as soil texture and pH, have been shown to be strong determinants of soil GHG fluxes, the impact of the legacy of previous management practices is less well understood. Here we aim to investigate the impact of such legacy effects and to contrast them against soil properties to identify the key determinants of soil GHG fluxes following digestate application. Soil from an already established field experiment was used to set up a pot experiment, to evaluate N2O, CH4 and CO2 fluxes from cattle‐slurry‐digestate amended soils. The soil had been treated with farmyard manure, green manure or synthetic N‐fertilizer, 18 months before the pot experiment was set up. Following homogenization and a preincubation stage, digestate was added at a concentration of 250 kg total N/ha eq. Soil GHG fluxes were then sampled over a 64 day period. The digestate stimulated emissions of the three GHGs compared to controls. The legacy of previous soil management was found to be a key determinant of CO2 and N2O flux while edaphic variables did not have a significant effect across the range of variables included in this experiment. Conversely, edaphic variables, in particular texture, were the main determinant of CH4 flux from soil following digestate application. Results demonstrate that edaphic factors and current soil management regime alone are not effective predictors of soil GHG flux response following digestate application. Knowledge of the site management in terms of organic amendments is required to make robust predictions of the likely soil GHG flux response following digestate application to soil. [ABSTRACT FROM AUTHOR]

Understanding how to manage N inputs to identify the practices that maximize N recovery has been an organizing principle of agronomic research. Because growth in N fertilizer inputs is expected to continue in an ongoing effort to boost crop production over coming decades, understanding how to efficiently manage recovery of fertilizer N will be important going forward. Yet synthesis of published data that has traced the fate of 15N‐labeled fertilizer shows that less than half of the N taken up by crops is derived from current‐year N fertilizer. The source of the majority of N in crops is something other than current‐year fertilizer and the sources are not really known. This is true for maize (only 41% of N in crops was from current‐year N fertilizer), rice (32%), and small grains (37%). Recovery of organic fertilizer N (manure, green manure, compost, etc.) in crops is low (27%), though N recovery in subsequent years (10%) was greater than that for mineral fertilizers. Thus, while research on efficiency of N fertilizer use through improved rate, type, location, and timing is important, this research fails to directly address management of the majority of the N supplied to crops. It seems likely that the majority of non‐fertilizer N found in crops comes from turnover of soil and crop residue N. We encourage the research community to revisit the mental model that fertilizer is a replacement for N supply from turnover of soil organic N (SON) and consider a model in which N fertilizer augments ongoing SON turnover and makes an important longer term contribution to SON maintenance and turnover. Research focused on the efficient recovery of N current‐year fertilizer inputs neglects this potential role for building soil N and managing soil N turnover, which seems likely to be the most important source of crop N. [ABSTRACT FROM AUTHOR]

Vicia L. is an invaluable genus with considerable agricultural and economic importance due to its high value as feed, green manure, and medicine. However, most of this genus is not well known and remains underutilized. Due to the imprecise circumscription and delineation of Vicia species, the taxonomic history of this genus is controversial, which has hindered the identification of species with high economic potential. Therefore, rapid and accurate identification of Vicia species is essential. Simultaneously, species identification through DNA barcoding has become an effective taxonomic classification tool. Here, the species‐discrimination abilities of matK, rbcL, trnH‐psbA, trnL‐trnF, ITS1, and ITS2 were tested in 161 Vicia species with both sequence similarity (nearest neighbor, best match, and best close match) and tree‐based (maximum likelihood tree) methods. Among the single barcode sites, trnH‐psbA had the highest level of polymorphism (52.4% variable sites; nucleotide diversity, 0.1338). Additionally, trnH‐psbA had the highest mean interspecific distance (0.1352) and intraspecific distance (0.0071). The combined barcode matK+trnH‐psbA had the highest correct identification rate by the sequence similarity method. Both trnH‐psbA (75.38%) and matK (70.73%) showed higher species discrimination rates than the other barcodes when using the tree‐based method. Based on overall performance, matK and trnH‐psbA, alone or in combination, were the best barcodes for Vicia. Internal transcribed spacer (ITS1) also showed good performance and provided essential information regarding nuclear DNA, so this site is also recommended as a backup barcode for Vicia. These Vicia barcodes can be used to identify species and to evaluate germplasm resource collections. [ABSTRACT FROM AUTHOR]

Green 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. [ABSTRACT FROM AUTHOR]

Common vetch (Vicia sativa L.) is an important annual forage legume. It is used as a cover crop, green manure, pasture legume and for silage and hay production. Its seeds can be used as a source of highly digestible protein and minerals in animal diets. However, their utilization as a feedstuff for monogastric animals is hindered by the fact that the seeds contain cyanogenic antinutritional factors that reduce their palatability. An effective utilization of V. sativa seeds as a successful monogastric feed stuff requires selection for higher protein availability and minimization of the cyanogenic antinutritional factors content. In this study, we selected one natural accession named Mjez Ibeb, from a collection of 25 accessions and cultivars, based on its superior agronomic performance and its naturally occurring genetic variation for cyanogenic traits. We investigated the genetic variation that exists for the cyanogenesis trait in more detail and analysed the seeds of 133 lines derived from accession Mjez lbeb. Of these, 40 naturally polymorphic lines that showed deficiencies in cyanogenesis and cyano‐amino acid content, were subsequently selected for detailed chemical analysis. Cyanogenic glucosides and cyano‐amino acid concentrations varied widely in the 40 lines. Multivariate analysis was performed and three lines (L16, L21, L18) with low content of cyanogenic compounds were identified. [ABSTRACT FROM AUTHOR]

Rice (Oryza sativa L.) straw is commonly incorporated into paddy soil after harvest, although it is not fully understood how the straw return strategy and its co‐incorporation with legumes affect soil productivity and rice performance. A 5‐yr experiment was conducted in a rice–rice–fallow or rice–rice–Chinese milk vetch (Mv, Astragalus sinicus L.) rotation in South China. Six treatments were included (i) a control with no fertilization and residue return, (ii) 100% of fertilizer recommendation (F100), (iii) 80% of F100 plus conventional return of rice straw (F80Rs), (iv) F80 plus Mv planting and incorporation (F80Mv), (v) co‐incorporation of F80Rs and F80Mv (F80RsMv), (vi) similar to F80RsMv except late rice straw was retained as high stubble (∼35 cm, F80RhMv). The results showed that, under reduced inorganic fertilizer input, grain yields in treatments with straw and/or Mv return were similar with those of F100. However, N uptake in early and late rice markedly increased by 8 to 14% and 30 to 53% in the co‐incorporation treatment F80RsMv compared with F100, respectively, as well as in the F80RhMv treatment for late rice. Significantly greater fertilizer use efficiency was obtained in the co‐incorporation practices. Although negative cumulative effects were observed for soil organic matter, total N, and available N after 5‐yr rotation, the magnitude of decline in the co‐incorporation treatments was much smaller than in others. Soil available P and K were accumulated in co‐incorporation practice, whereas pH was less affected. Overall, the study suggested that the combination of rice straw and leguminous green manure is a promising practice to produce more grain yield with less fertilizer inputs in subtropical double‐rice production. [ABSTRACT FROM AUTHOR]

Root lesion nematodes are pathogens that have been causing relevant losses in crops; therefore, assertive management procedures to control them must be put in practice. Thus, the aim of the present study is to assess Pratylenchus zeae and P. brachyurus reproduction in green manure maize/soybean consortium and in single management systems. Initially, maize was cultivated for 60 days in naturally infested soil to enable nematode multiplication. Next, soil and roots in the pots were homogenized and the initial population was determined. The sampled soil was placed in pots containing green manure. Stizolobium aterrimum, Cajanus cajan, Canavalia ensiformis, Crotalaria spectabilis and C. juncea were sown alone or in maize/soybean consortium. Only one crop was used as control. The experiment was repeated in two different periods. Overall, the single and the consortium treatments reduced the nematode population per root gram, as well as the total population in the root system in experiments with P. zeae. The consortium treatments did not reduce the nematode population in treatments with P. brachyurus. On the other hand, the single crop treatments were efficient in controlling both nematode phytoparasites. [ABSTRACT FROM AUTHOR]

Management strategies are sought to minimize wind erosion of irrigated agricultural soils along the Columbia River of the Inland Pacific Northwest (PNW), particularly during the early season (March–April) when high winds coincide with sowing of vegetable crops. Early-season wind erosion potential from soil-incorporated green manure (i.e., incorporation of a cover crop of mustard into the soil in autumn) and no green manure treatments was assessed at two locations over 2 yr using a portable wind tunnel. Incorporation of green manure the preceding autumn did not influence wind erosion or soil erodible characteristics the following spring. Soil-incorporated green manure, however, did influence early-season crop residue characteristics. Although differences were significant, low residue cover and stem silhouette area suggested relatively small differences in empirical estimates of windblown soil loss between manure treatments. Soil crusting resulting from irrigation and/or rainfall prior to assessing wind erosion may have masked any influence of green manure on wind erosion. Due to the high erosion rates measured from the crusted soils, multiple years of green manure or minimum or reduced tillage may be required to promote aggregation and/or enhance residue cover and thereby reduce wind erosion of irrigated soils. [ABSTRACT FROM AUTHOR]

Straw and green manures are among the most important soil amendments used worldwide to provide agricultural soil with organic matter (OM). The reported improvement in soil organic matter content varies greatly; therefore, there is a need for mechanistic approaches to evaluate substrate turnover in the soil. This study compares the results of a field and an incubation experiment to follow the fate of carbon from organic fertilizers in soil as a function of the C:N ratio of the amendments. The amendments were straw (small-N, Hordeum vulgare L.; large-N, Pisum sativum L.) or green manure ( Sinapis alba (M)) with additional organic or mineral fertilizers to alter the C:N ratio of the soil-substrate mixture. In the 100-day field study, C respiration was measured at defined intervals at three locations with different soil types (Luvisol, Fluvisol and Arenosol). In the incubation experiment, C changes over 300 days were quantified based on the measurement of C respiration and C amounts in the soil-substrate mixture at the start and end of the experiment. Furthermore, microbial biomass was quantified at the end of the experiment to enable an assessment of microbial C-use efficiency. In the field experiment, a significant correlation between N supply and C fate occurred at one site only (Luvisol) where retention of C from organic substrates was larger with increased N supply. In the incubation experiment, N supply and C fate were correlated significantly for both soils under study (Arenosol and Fluvisol). Furthermore, C-use efficiency was positively correlated with C retention from organic inputs to the Fluvisol in the incubation experiment, whereas the opposite situation occurred with the Arenosol. This indicated that C retention from organic inputs was not dependent on carbon-use efficiency by the microbial community under these conditions. We conclude that stoichiometric implications apply to carbon retention in soil that depend on N availability for soil microbes. In the early stages of organic matter turnover, the outcome of N availability might be concealed by the effect of chemical recalcitrance of the substrates. The length of this phase will depend on environmental conditions for microbial activity. The effect of the C:N ratio on the fate of C from organic amendments must be considered in the assessment of C management strategies in arable farming. Highlights Organic inputs to soil with a large C:N ratio lose more C in turnover than amendments with a small C:N ratio., Retention of C from organic amendments in soil appears to depend on microbial C-use efficiency and availability of nitrogen., The soil type and related environmental conditions affect CUE and the magnitude of C retention., Negative correlation between C:N ratio of organic amendments and C fate in soil must be considered in carbon management strategies. [ABSTRACT FROM AUTHOR]

Roots of agricultural crops, including maize, are hosts of different microorganisms, many beneficial, like plant growth and health-promoting arbuscular mycorrhizal fungi ( AMF), as well as pathogens including Pythium, Polymyxa and Microdochium. To improve crop nutrition and health, profound knowledge is required regarding how agricultural practices affect field populations of root-associated microorganisms. Hence, the objective of this work was to evaluate the effect of crop genotype and organic fertilizers on the plant growth performance of maize and their root-associated microorganisms. The experiment was conducted as a fully factorial greenhouse pot experiment with maize cultivars (two land races and two hybrids) and organic fertilizers (green manure, cow manure and compost) as the two main factors. Plants were harvested 8 weeks after sowing. In general, the different maize cultivars responded similarly to the applications of the organic fertilizers. Cow manure and compost increased plant growth, whereas green manure had limited effect on plant growth. Root colonization with AMF was reduced by green manure with rape. Infection with the root pathogens Pythium and Polymyxa was reduced by all organic fertilizers, whereas in contrast, infection with Microdochium increased with the majority of the organic fertilizers applied. In conclusion, both maize genotype and organic fertilizers affect the abundance of AMF and root pathogens in maize, which should be considered when developing management strategies of these root-inhabiting microorganisms. [ABSTRACT FROM AUTHOR]

The use of antagonist plants is one of the most effective methods in the management of root-knot nematodes, and several plants recommended for this purpose are nitrogen-fixing plants that act as green manure because of the amount of mass produced. The mode of action of some species has already been investigated, but this has yet to be elucidated for many plants researched as antagonists. Thus, this study aimed to assess the penetration and reproduction of Meloidogyne javanica on the root system of three species of crotalaria, as well as Mucuna deeringiana, Cajanus cajan, Canavalia ensiformis, Macrotyloma axillare and Stylosanthes capitata, with soya bean used as control treatment. Thus, plants inoculated with the nematode were assessed 5, 10, 15 and 20 days after inoculation ( DAI), for nematode penetration and development. After 60 days of inoculation, the nematode reproduction factor (RF) was assessed. The plants did not prevent M. javanica penetration, which differed at varying degrees, according to the time of assessment and the plant species investigated. However, the nematode reproduction was impaired in all the leguminous crops assessed, with ( RF)<1 in all the plants, while in soya bean the RF values were 2.85 and 2.56, in the respective experiments. [ABSTRACT FROM AUTHOR]

Direct seeding is a promising technique for ecological restoration, but it has been poorly studied in neotropical savannas. Different types of plant cover (no cover, crops, or green manure) and fertilization (unfertilized, synthetic fertilizer, or poultry litter) were used to verify if survival and growth of different tree species after direct seeding could be enhanced by the use of any combination of these techniques. Seedling emergence, establishment, and growth were followed for 2 years for six savanna tree species sown in an agricultural field in Central Brazil. Germination was high (52%, on average) for Anacardium occidentale, Aspidosperma macrocarpon, Hymenaea stigonocarpa, Dipteryx alata, Eugenia dysenterica, and Magonia pubescens. Six additional species were planted, but less than 5% of these seeds germinated. Crops (60% shade) did not affect seedling survival and biomass compared with the control treatment, supporting the use of this strategy during the initial phase of restoration to involve farmers in the process. In contrast, the excessive shading (95%) from the green manure treatment decreased the survival of two species and the growth in biomass and diameter of five species, especially when combined with fertilization. Seedling growth was very slow throughout the experiment, requiring extended weed management. This study supports the use of direct seeding of the studied species for savanna restoration, but methods could be improved to include a larger number of species. [ABSTRACT FROM AUTHOR]

A 2 year field experiment was conducted in northern Greece to study the biomass effects of four oregano ( Origanum vulgare) biotypes, used as incorporated green manure, on the emergence and growth of barnyard grass ( Echinochloa crus-galli), bristly foxtail ( Setaria verticillata), common purslane ( Portulaca oleracea), cotton ( Gossypium hirsutum), and corn ( Zea mays). The oregano biotypes were selected on the basis of their high phenolic content. The phytotoxic potential of the oregano biotype extracts also was determined in the laboratory by using a perlite-based bioassay with cotton, corn, and barnyard grass. The bioassays indicated that the germination, root elongation, and fresh weight of cotton, corn, and barnyard grass were reduced by the oregano biotype extracts. In the field, the emergence of common purslane, barnyard grass, and bristly foxtail was reduced by 0-55%, 38-52%, and 43-86%, respectively, in the oregano green manure treatments, as compared with the oregano green manure-free treatments (the controls). At harvest, the cotton lint and corn grain yields in the oregano green manure treatments were 24-88% and 5-16%, respectively, greater than those in the corresponding green manure-free, weedy treatments. These results indicated that when the biomass of the oregano biotypes with a high phenolic content were incorporated into the soil as green manure, they could be used to suppress barnyard grass, bristly foxtail, and common purslane in cotton and corn and consequently to minimize herbicide usage. [ABSTRACT FROM AUTHOR]

Alternative N fertilizers that stimulate low greenhouse gas emissions from soil are needed to reduce the impact of agriculture on global warming. Corn (Zea rnays L.) grown in a calcareous silt loam soil in northwestern Italy was fertilized with a municipal solid waste compost and vetch ( Vicia villosa Roth.) green manure. Their potential to reduce N2O and CO2 emissions was compared with that of urea (130 kg N ha-1) Gaseous fluxes were measured for 2 yr in the spring (after soil incorporation of fertilizers) and in summer. In spring, the slow mineralization of compost reduced N2O emissions (0.11% of supplied N) relative to urea (3.4% of applied N), without an increase in CO2 fluxes. Nitrous oxide (2.31% of fixed N) and CO2 emissions from rapid vetch decomposition did not differ from urea. When N2O and CO2 fluxes were combined, compost reduced by 49% the CO2 equivalent emitted following urea application. Vetch did not show such an effect. In summer, no fertilizer effect was found on N2O and CO2 emissions. Compost proved to be potentially suitable to reduce the CO2 equivalent emitted after soil incorporation while vetch did not. For a thorough evaluation, net greenhouse gas emissions assessment should be extended to the entire N life cycle. Differences between calculated N2O emission factors and the default Tier 1 value of the Intergovernmental Panel on Climate Change (1%) confirmed the need for site- and fertilizer-specific estimations. [ABSTRACT FROM AUTHOR]

Habitat loss and reduction in quality, together with increasing homogeneity of the farmed landscape and more intensive field management, are believed to be major drivers of biodiversity loss on farmland. Organic farms demonstrate features that are now rare elsewhere in UK farming systems, such as crop rotations incorporating grass leys, exclusion of synthetic pesticides and fertilizers, and reliance on animal and green manures. They may also contain greater densities of uncropped habitats such as hedgerows. In this study, we examined whether organic farming affected populations of one group of insects of conservation interest, butterflies, on farmland. The abundance of butterflies on pairs of organically and conventionally managed farms was recorded over 3 years and a number of habitat and crop variables, likely to be related to butterfly abundance, were also measured. Organic farms attracted significantly more butterflies overall than conventional farms. Significantly more butterflies in both farming systems were recorded over the uncropped field margin than the crop edge. The difference in butterfly abundance between crop edge and field margin was relatively greater in conventional than organic systems. Species richness of butterflies tended to be greater on organic farms. Five species of butterfly were significantly more abundant on organic farms in at least 1 year, while no species was significantly more abundant on conventional farms. Organic and conventional cropping patterns differed, the former having proportionally more grass leys, and hedgerows were larger on organic farms. Although no significant effects of farming system on the numbers of grass or forb species present in the field margin or crop edge were detected, some individual plant species showed differences in frequency between organic and conventional field boundaries. Increasing the extent of organic farming, or practices associated with it, could help to restore biodiversity in agricultural landscapes. [ABSTRACT FROM AUTHOR]

Legume-containing leys are commonly used to improve soil fertility in the 2-year conversion period from conventional to organic production. While in-conversion land may be grazed, in stockless farming systems, land is effectively out of production, leading to a reduction in income and pressure on cash flow. The impacts of seven organic conversion strategies on the first organic crop (winter wheat) were previously reported. This study investigates the effect of the conversion strategies on the second (winter beans) and third (winter oats) organic crops, thereby extending the analysis throughout the first complete rotation. The strategies were (a) 2-years’ red clover–ryegrass green manure, (b) 2-years’ hairy vetch green manure, (c) red clover for seed production then a red clover–ryegrass green manure, (d) spring wheat undersown with red clover, then a red clover green manure, (e) spring oats, then winter beans, (f) spring wheat, then winter beans and (g) spring wheat undersown with red clover, then a barley–pea intercrop. Conversion strategy had a significant impact on organic bean yield, which ranged from 2.78 to 3.62 t ha−1, and organic oat yield, which ranged from 3.24 to 4.17 t ha−1. In the organic bean crop, weed abundance prior to harvest, along with soil texture, accounted for 70% of yield variation. For the oats, soil mineral nitrogen in November together with weed abundance in April accounted for 72% of the variation in yield. The impacts of conversion strategies on soil mineral nitrogen levels were still detectable 3 years after conversion. The results from this study indicate that the choice of conversion crop has important long-term implications. More exploitative conversion strategies, that is those with a higher proportion of cash cropping, had an increased weed burden and decreased levels of soil mineral nitrogen, leading to reduced yields of beans and oats, 2 and 3 years after conversion. [ABSTRACT FROM AUTHOR]

Field experiments were conducted at the Directorate of Rice Research experimental farm, ICRISAT campus, Patancheru, Hyderabad, during 1998–2000 for five consecutive seasons (three wet and two dry seasons) with five treatments [T1 – 100 % straw incorporation; T2 – 50 % straw incorporation; T3 – 100 % straw + green manure (GM) incorporation; T4 – 100 % straw burning and T5 – 100 % straw removal (control)] along with the recommended dose of fertilizers to evaluate the effect of different crop residue management (CRM) practices on yield components and yield of rice in rice–rice cropping sequence. The ammonium N measured at active tillering was higher in 100 % straw-added plots over 50 % straw addition and straw removal with maximum values in the straw + GM-incorporated plots. Among the yield components, tillers, panicles and spikelets were influenced from the second season of residue incorporation with significant increase in 100 % straw-added treatments. The increase in tiller and panicle number could be attributed to the increased NH4-N in these treatments, which is evident from the significant correlation between tiller number and NH4-N (r = 0.82**) and panicle number and NH4-N (r = 0.87**). The influence of residue treatments on rice grain yield was observed from the third season onwards where incorporation of straw alone or in combination with GM and burning of straw significantly increased grain and straw yields. Grain yield showed significant positive correlation with the number of tillers (r = 0.74*–0.81**) and panicles (r = 0.74*–0.84**) in three treatments (T1, T3 andT4) where grain yields were significantly higher. The regression analysis showed that 57–66 % and 64–75 % of the variation in yield could be explained by tillers and panicles together in these three treatments during wet and dry seasons respectively. Thus, CRM practices such as addition of 100 % straw either alone or with GM and straw burning influenced the yield components (tillers, panicles and spikelets) positively and thereby increased rice grain yields. [ABSTRACT FROM AUTHOR]

Crop establishment, determined by shoot and root growth during early growth is a vital component in procuring desired plant populations and high yields in rainfed tropical smallholder farming systems, where green manures help maintain soil fertility and sustainability. As green manure incorporation could affect early seedling growth, studies were conduced in a plant house using soils from fields, to evaluate the impact of incorporating two popular tropical green manures (Crotalaria juncea and Tithonia diversifolia) into soil under rainfed field conditions over 3 years, on selected physico-chemical properties of the soils and on establishment and early shoot and root growth of maize (Zea mays), with and without inorganic fertilizers. In a given year, green manure was grown in one season while maize was grown in the other. A soil that did not receive green manures but was left fallow during the period of green manure cultivation was used as the control treatment. The incorporation of green manures over the 3 years showed trends of increasing soil physical properties, and also the available nitrogen, phosphorus and potassium contents. Incorporation of Crotalaria, with its higher nitrogen content, promoted shoot growth, while Tithonia induced the development of an extended root system. The use of inorganic fertilizers stimulated the beneficial impact of the green manures in promoting shoot and root growth. The use of green manures, especially Tithonia, promoted the development of seminal and nodal roots of maize seedlings, both in the form of length and thickness (based on root surface area) and root length densities, which could assist in successful crop establishment and resource utilization, rather than primary roots. The benefits of using green manures, especially Tithonia, in promoting root growth and Crotalaria in shoot development of maize seedlings even without inorganic fertilizers is presented. [ABSTRACT FROM AUTHOR]

Incorporating green manure crops into soil may increase P bioavailability for succeeding crops. We conducted a greenhouse study to evaluate the effects of green manures on biomass and P utilization of a succeeding grain sorghum [Sorghum bicolor (L.) Moench] crop. Four perennial forages and four winter annual cover crops were grown in pots, killed, and incorporated into the soil before planting sorghum in the same pots. Sorghum P uptake was positively correlated with perennial forage P uptake. Among winter cover crops, sorghum P uptake following white lupine (Lupinus albus L.) was lower than in all other treatments, including the control (no previous cover crop), even though lupine biomass, N content, and P uptake were two to three times greater than those of the other winter cover crops. Phosphorus uptake differed slightly among the other three winter cover crops but sorghum P uptake was not correlated to winter cover crop P uptake. Thus, among winter cover crops, plant type rather than P uptake seemed to influence the subsequent sorghum crop's P uptake. However, sorghum biomass following the three winter cover crops other than lupine was greater than sorghum biomass in the control treatment, indicating that there was a beneficial cover crop rotation effect among these three winter cover crops. Soil samples were collected and analyzed for Bray-1 P when green manure crops were planted, when they were incorporated into the soil, when sorghum was planted and when sorghum was harvested. These data showed that the Bray-1 soil P test has little potential to predict differences in P uptake and release among different types of green manures and it has limited potential to predict P uptake by sorghum following incorporation of green manures. [ABSTRACT FROM AUTHOR]

Presents information on a study which examined the palatability of carrots and green manure crops to white-tailed deer. Methodology; Results of the study; Discussion.

Evaluates the effects of using legume green manure and nitrogen fertilizer on crop yields and nitrogen dynamics of an irrigated rice and wheat cropping system. Changes in the removal and recovery of nitrogen by rice and wheat; Rice yields before and after fertilizer treatment; Residual effects of green manure of wheat.

Long term incubation studies to determine the nitrogen (N) mineralization rates and kinetics in soils freshly amended with some commonly used green manures such as Seshania rostrata, Gliricidia maculata, Leucaena leucocephala and Azolla pinnata are scarce. A long term aerobic study was, therefore, conducted by incubating soils freshly amended with the above-mentioned green manures in PVC columns at 35 ± 1°C and with 0.01 Mpa moisture content. The soils were then leached at periodic intervals for up to 36 weeks. The N-mineralization rates were greatest during the first week and decreased with time in all soils. The green manure amended soils leached 247 mg kg-1 more NO3 + NO2 - N than the unamended control. In general, the total N mineralized (mean 61%) was almost twice that of net N mineralized (mean 30%) in the amended soils. The percent N mineralized (total and net), however, varied with the nature of green manure incorporated into the soil. It was greatest in the soil amended with sesbania and lowest in the soil amended with azolla. The kinetic parameters derived using the double exponential model indicated that green manure amended soils possessed significantly higher N-mineralization potentials and rate constants compared to the unamended control. The kinetic parameters also varied with the nature of green manure incorporated into the soil. Among the various parameters lignin content, lignin to N ratio and lignin + polyphenol to N ratio of the green manures were the key factors governing the rate of decomposition and subsequent N mineralization from the amended soils. [ABSTRACT FROM AUTHOR]

In two field trials with rotations of sugar beet-cereals-green manure the population dynamics of Heterodera schachtii was investigated as well as the frequency of its fungal egg parasites. During the rotation, highest rates of fungal parasitism (20-48 %) were observed after years with sugar beet, independently of the nematode population density. In the interim parasitism decreased to about 10%. A highly significant correlation was found between nematode population density and the amount of parasitized eggs and larvae. The effect of resistant catch crops (oil radish 'Pegletta' and white mustard 'Maxi') on fungal egg parasites was not different from the effect of Phacelia or fallow. There are indications, however, that a high nematode multiplication on a susceptible catch crop promotes antagonistic fungi and, in consequence, a nematode population decrease may occur in the following sugar beet crop. [ABSTRACT FROM AUTHOR]

In a field experiment conducted during 1992-95 at Lucknow, India, sugarcane was planted in rows 60 and 90 em apart in three crop rotations (rice-sugarcane-ratoon, Sesbania aculeata for green manure-sugarcane-ratoon, and cowpea-sugarcane-ratoon) with 0, 150 and 300 kg N ha-1 as urea either with or without farmyard manure iFYM) at 10 t ha-1. Sugarcane yields were significantly greater in the Sesbania rotation than in the other because of a larger N uptake. N uptake of the crop was significantly affected by soil organic carbon, and available N and K contents, Ratoon yields, however, were largest in the cowpea sequence followed by the rice rotation, probably due to a prolonged residual effect of cowpea and rice root residues. The residual effect of a Sesbania green manure was negligible as demonstrated by the low NO3N content of the soil profile after sugarcane harvest compared to the other two crop sequences. The total cane productivity (main sugarcane plus ratoon) was greater (156 t ha-1) in the cowpea rotation than the Sesbania (152 t ha-1) and rice (140 t ha-1) rotations. [ABSTRACT FROM AUTHOR]

Field experiments were conducted at Tamil Nadu Rice Research Institute, Aduthurai, India, during the wet seasons of 1992 and 1993 to study the effect of full and partial substitution of fertiliser N with green manure N (Sesbania rostrata) on nitrogen uptake, yield attributes and yield of rice. The experiment consisted of eight treatments with two levels of N (100 and 200 kg ha-1) and three sources of N application viz., fertilizer, integrated (1:1 fertilizer and green manure N) and green manure N compared to the recommended practice (150 kg fertilizer plus 6.25 t ha-1 (72 kg N) green manure) and a no N control. Nitrogen application markedly increased the N uptake. Combined use of the two N sources at 200 and 222 kg N ha-1 and of single fertilizer N at 200 kg N ha-1 recorded the maximum N uptake, increased the yield attributes such as number of panicles per unit area, weight per panicle, number of total and filled grains per panicle and test weight. At 200 kg N ha-1 full substitution of N by green manure reduced the grain yield but only partial substitution of N by green manure resulted in almost similar yield as single fertilizer N. Thus 200 kg N ha-1 applied in equal proportions of fertilizer and green manure N can be recommended for medium duration rice cultivars. [ABSTRACT FROM AUTHOR]