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The management adopted in the establishment and replanting of sugarcane fields, with conventional tillage followed by fallow, is one of the main causes of soil quality degradation. In this context, the soil quality index (SQI) is an important tool to guide the use of more sustainable practices and management. This study aimed to monitor the effect of different cover crops in association with different tillage systems on sugarcane yield based on key indicators and an SQI developed using the Soil Management Assessment Framework (SMAF). The experiment was carried out on a sugarcane expansion area located in the municipality of Ibitinga, São Paulo, Brazil. The following soil physical and chemical attributes were analyzed: soil bulk density, macroaggregates, available phosphorus and potassium. Soil carbon content was also analyzed and used to calculate the SQI. Productivity over the 4 years of sugarcane cultivation was also analyzed. The use of subsoilers for soil tillage proved efficient in managing compaction by providing lower soil bulk density values in the first years of cultivation (1.59 and 1.63 g cm−3); however, these effects occurred in the short term with a 10% increase in later years. The use of millet in association with subsoiling showed the best results for soil quality (0.59), reflected in the maintenance of yields at 100 Mg ha−1 over time. Thus, our study reinforces the importance of using soil conservation systems in sugarcane replanting areas to achieve production longevity. [ABSTRACT FROM AUTHOR]

The slow initial growth of hybrid brachiariagrass (Urochloa spp.) can require some months to achieve complete ground cover of a newly seeded area, leading to decreased forage production and increased weed infestation in the establishment year. To solve these problems, we attempted to sow seeds by mixing warm‐season annual forages with brachiariagrass at a brachiariagrass pasture establishment (University of Florida, USA, 2017 and 2018). Treatments were single seeding of 'Cayman' brachiariagrass solo (BR), sorghum sudangrass solo (Sorghum bicolor (L.) Moench; SD), and sunn hemp solo (Crotalaria juncea L.; SH) and two mixtures of these three forages at half (HSR) or full (FSR) of the recommended seeding rate. The seeding rates of FSR were, respectively, 10, 20, and 25 kg/ha for brachiariagrass, sudangrass, and sunn hemp. The treatments were distributed in a randomized complete block design with four replicates. Plots were harvested at 6, 12, 18, and 24 weeks after seeding. The number of brachiariagrass seedlings in the HSR and FSR treatments was less than half that in the BR (P <.05). The BR treatment had greater brachiariagrass herbage accumulation (HA) at all harvests than HSR (4%–75% of BR) or FSR (7%–66% of BR). This difference between the BR and mixture treatments became narrower in later harvests. In addition to the decreased number of brachiariagrass seedlings, light and nutrient competition between annual forages are considered to be the causes of lower brachiariagrass HA in the mixture treatments. Sunn hemp increased forage HA and crude protein concentrations at 6 weeks. Sudangrass provided overyielding forage until 18 weeks after seeding, with a similar nutritive value as brachiariagrass. Mixing warm‐season annual forages with brachiariagrass at the establishment, especially half of the seeding rates of sunn hemp and sudangrass, is a feasible management practice to increase HA during the first 12 weeks after seeding. [ABSTRACT FROM AUTHOR]

Soil tillage is an agricultural practice that directly affects the global carbon cycle. Our study sought to assess the implications of adopting sunn hemp cover crops with different tillage practices on CO2 emissions for two soil types (clayey and sandy soil) cultivated with sugarcane in Brazil. The experimental design was a split‐plot with randomized blocks, with the main plots being with cover crop or fallow and sub‐plots being under conventional or minimum tillage. Our results indicate that during the first 50 days after soil tillage, the variation in soil CO2 emissions was stimulated by cover crop and soil tillage, while after that, it became dominated by the root respiration of sugarcane plants. We also found that over the first 97 days after the tillage, the clayey soil showed differences between minimum tillage with cover crop and fallow. Conversely, for sandy soil over the first 50 days following, there were differences between the tillage systems under cover cropping. Emissions from sugarcane rows were found to be greater than those from inter‐row positions. We concluded that soils under different textural classes had distinct patterns in terms of soil CO2 emissions. The correct quantification of CO2 emissions during the sugarcane renovation period should prioritize having a short assessment period (~50 days after soil tillage) as well as including measurements at row and inter‐row positions. [ABSTRACT FROM AUTHOR]

Low productivity and nutritive value of cool-season perennial forages, such as tall fescue [Schedonorus arundinaceus (Schreb.) Dumort.] during summer necessitates the identification of warm-season forages that improve nutritive value and yield of cool-season-based forage systems. A fast-growing, warm-season tropical legume sunn hemp (Crotalaria juncea L.) has the potential to accomplish this. Our objectives were to evaluate herbage accumulation and nutritive value (crude protein [CP], in vitro true digestibility [IVTD], neutral detergent fiber [NDF], acid detergent fiber [ADF], and NDF digestibility [NDFD, 48 h]) of sunn hemp harvested 35, 45, and 55 d after planting (DAP) at 10- and 15-cm heights and to determine regrowth potential when harvested 20 d after each initial harvest over two consecutive years. Sunn hemp herbage accumulation averaged 1.9 and 3.1 Mg ha-1 at 45 and 55 DAP, respectively. Herbage accumulation of initial harvest increased linearly from 35 to 45 to 55 DAP by 119 and 57%, respectively. Herbage accumulation of regrowth after the 35 DAP initial harvest was 262 and 303% greater than the 45 and 55 DAP initial harvests, respectively. Cutting height did not affect (P > 0.05) any variables. The greatest CP (154 g kg-1 dry matter) was observed at 35 DAP and decreased linearly with DAP. Both NDF (P < 0.01) and ADF (P = 0.01) concentrations increased linearly with DAP for both initial and regrowth harvests. The IVTD of initial and regrowth harvests averaged 794 and 624 g kg-1 dry matter, respectively. Forage NDFD for initial and regrowth harvests averaged 487 and 392 g kg-1 NDF, respectively. Nutritive value and herbage accumulation of sunn hemp can be optimized by initially harvesting between 35 and 45 DAP, and leaving at least 10 cm of residue to allow for regrowth. [ABSTRACT FROM AUTHOR]

Farmers in the inland valleys of northern Ghana are challenged with nitrogen (N) deficiency as a major production constraint of rainfed lowland rice ( Oryza sativa L.). With extremely low use of external inputs, there is a need to efficiently use the systems' internal resources such as native soil N. Largest soil nitrate-N losses are expected to occur during the transition between the dry and wet season (DWT) when the soil aeration status changes from aerobic to anaerobic conditions. Technical options avoiding the build-up of nitrate are expected to reduce N losses and may thus enhance the yield of rice. A field study in the moist savanna zone of Ghana assessed the in situ mineralization of native soil N, the contribution of nitrate to the valley bottom by sub-surface flow from adjacent slopes, and the effects of crop and land management options during DWT on seasonal soil Nmin dynamics and the yield of lowland rice. Large amounts of nitrate accumulated during DWT with a peak of 58 kg ha−1 in lowland soils, of which 32 kg ha−1 were contributed from the adjacent upland slope. Most of this nitrate disappeared at the onset of the wet season, possibly by leaching and denitrification upon soil flooding. While the incorporation of rice straw (temporary immobilization of soil N in the microbial biomass) had little effect on soil N conservation, growing a crop during DWT conserved 22-27 kg of soil N ha−1 in the biomass and Crotalaria juncea supplied an additional 43 kg N ha−1 from biological N2 fixation. Farmers' practice of bare fallow during DWT resulted in the lowest rice grain yield that increased from 1.3 (2.2) to 3.9 t ha−1 in case of the transition-season legume. Growing a pre-rice legume during DWT appears a promising option to manage N and increase lowland rice yields in the inland valleys of northern Ghana. [ABSTRACT FROM AUTHOR]

Adoption of sunn hemp (Crotalaria juncea L.) as a cover crop has been limited primarily due to the availability of seed sources, leading to high seed costs and unreliable supplies. Seed production in Florida with the commercially available sunn hemp cultivar Tropic Sun has been largely unsuccessful. An experiment was designed to evaluate 16 accessions of sunn hemp for potential commercial seed production in Florida at three planting dates (May, June, July). Vegetative and reproductive characteristics were evaluated to provide baseline information for future development of a cultivar of sunn hemp that could produce seed in Florida with desirable cover crop attributes. The results indicate that the sunn hemp accessions could be separated into two groups. Regardless of planting date, accessions in Group 1 (PI 234771, PI 248491, PI 295851, PI 337080, PI 468956, PI 561720, PI 652939) displayed desirable cover crop characteristics, such as high biomass production and leaf area. Accessions in Group 1 had a short-day flowering response and produced few to no pods and seeds. Group 2 accessions (PI 207657, PI 250485, PI 250486, PI 250487, PI 314239, PI 322377, PI 346297, PI 391567, PI 426626) were less sensitive to photoperiod, were generally smaller plants because of earlier transition to reproductive growth, and produced more seedpods and seeds. Seed production was generally better when seeds were sown at the earliest date. It appears that in Florida, sunn hemp accessions that are capable of flowering in summer rather than fall have greater potential for seed production. [ABSTRACT FROM AUTHOR]

Economic and environmental impacts of ethanol biorefineries with different sugarcane ( Saccharum spp.) production technologies are evaluated with a focus on harvesting systems, reduced tillage, controlled traffic farming to reduce soil compaction, and alternatives of sugarcane rotation. Results showed that scenarios with sunn hemp ( Crotolaria juncea) as a rotation crop in the sugarcane cycle present great potential to decrease environmental impacts of sugarcane biorefineries. Although reduced tillage promotes a reduction in sugarcane production costs in comparison to conventional tillage, it only cause a slightly decrease (less than 5%) on ethanol environmental impacts. Use of soybean ( Glycine max) as a rotation crop yields an extra source of income, increasing the net agricultural revenues by 15% compared to scenario with sunn hemp. However, better economic and environmental impacts for sugarcane biorefinery are obtained with use of sunn hemp in the crop rotation and controlled traffic farming. Sugarcane production using controlled traffic farming allows an increased number of harvesters, with consequent reduction of 43% in greenhouse gases emissions, 24% in fossil depletion, and 44% in acidification potential when compared to burned cane scenario. These results reinforce that better agricultural management practices should be used to maximize number of cuts in the sugarcane cycle. © 2015 Society of Chemical Industry and John Wiley & Sons, Ltd [ABSTRACT FROM AUTHOR]

Sunn hemp (Crotalaria juncea L.) is an annual plant widely grown in the tropics. The genus Crotalaria includes some species known to be toxic to animals. Development of seedproducing cultivars for the continental United States at Auburn University, AL, has raised the question of whether its seeds and forage are toxic. This review will present the evidence reported in the literature on the presence of toxic compounds in sunn hemp seed and foliage and other Crotalaria species found in the United States and their effect on animals. Results from research on sunn hemp demonstrate it is a valuable source of forage without toxic effects. The seed does not cause acute toxicity to domestic animals because it has only a small amount of the toxic pyrrolizidine alkaloids characteristic of the genus Crotalaria. Therefore, its presence as a feed contaminant does not pose a problem. However, sunn hemp seed should not be incorporated in animal diets because, depending on the amount in the diet and the length of time that the diet is fed, it may cause weight loss and potential death. Conflicting reports found in the literature regarding seed toxicity of C. juncea appear to be caused by the amount of seed included in the diet, length of time the diet was fed, and animal species that consumed it. Statements indicating that sunn hemp forage is toxic seem to be due to misinterpretation of the literature and unwarranted extension of the toxicity problems found in other Crotalaria species to sunn hemp. [ABSTRACT FROM AUTHOR]

Impact of cover crops (CCs) on winter wheat (Triticum aestivum L.) and grain sorghum [Sorghum bicolor (L.) Moench] yields is not well understood. We assessed crop yield and its relationships with CC-induced changes in soil properties for a 15-yr CC experiment in wheat-sorghum rotation at 0, 33, 66, and 100 kg ha-1 of N application in south central Kansas. Hairy vetch (Vicia villosa Roth) was used as a winter CC from 1995 to 2000, while sunn hemp (SH; Crotalaria juncea L.) and late-maturing soybean [LMS; Glycine max (L.) Merr.] were used as summer CCs in no-till from 2002 to 2008. Summer CCs increased crop yields particularly at low rates of N application. At 0 kg N ha-1, SH increased sorghum yield by 1.18 to 1.54 times, while wheat yield increased by 1.60 times in the first year (2004) after CC establishment relative to non-CC plots. At 66 kg N ha-1, SH had no effects on sorghum yield, but it increased wheat yield in 2 of 3 yr. Cover crops increased soil total N pool by 270 kg ha-1 for the 0- to 7.5-cm depth. Crop yield increased with the CC-induced decrease in soil maximum compactibility (soil's susceptibility to compaction) and soil temperature, and increase in soil aggregate stability, soil organic carbon (SOC) and total N concentration, and soil water content, particularly at 0 kg N ha-1. Principal component analysis (PCA) selected soil compactibility and total N as the best yield predictors. Inclusion of summer legume CCs in no-till fixes N, increases crop yield, and improves soil-crop relationships. [ABSTRACT FROM AUTHOR]

This article discusses the leaching of the pesticide atrazine and its degradates in the shallow groundwater of southeastern Florida. According to the authors, fields of sweet corn have hydrologic conditions with a potential for shallow groundwater contamination. They found that planting a cover crop like Sunn Hemp during the summer and then turning and chopping crop residues into the soil significantly reduces atrazine leaching. The results demonstrate a small but significance risk for groundwater contamination by leaching of atrazine in south Florida.

Legumes used as green manure (GMN) may provide on-farm sources of N for subsequent crops. In warm-humid climates on sandy soils, however, there is a need to evaluate effects on growth and yield of subsequent crops when GMN substitutes for chemical N fertilizer. We collected time-series data for 2 years to evaluate growth and ear yield response of sweet corn ( Zea mays L. var. Rugosa) in annual rotation with GMN (summer, winter or summer plus winter GMN) and supplemented with 0, 67 or 133 kg chemical N ha−1. Control treatments receiving 0, 67, 133, 200 or 267 kg chemical N ha−1 were used for comparison. Rotation with summer plus winter GMN resulted in more growth and yield benefit for sweet corn than did the other GMN rotations. Compared with control treatments receiving the same chemical N rates, rotation with summer plus winter GMN increased sweet corn ear yield, leaf area index and total plant dry weight and N content by 15–30 %. Despite these benefits, use of high chemical N rate (267 kg chemical N ha−1) resulted in ear yields at least 20 % greater than sweet corn rotated with any GMN and fertilized with reduced N rates. Largest increases in sweet corn dry weight and N content occurred between 4 and 6 weeks after emergence in all treatments. After this period of rapid growth, sweet corn fertilized with 267 kg chemical N ha−1 showed higher N content than all other treatments. Prior to this period of rapid growth, multiple rainfall events in excess of 30 mm may have resulted in leaching of N from GMN residue. Considering the high rainfall levels, low water and N retention capability of sandy soils and rapid N release from GMN during decomposition, future research of GMN in this environment should evaluate options to better match GMN termination with time of greatest potential N uptake from a subsequent crop. [ABSTRACT FROM AUTHOR]

Sunn hemp seeds contain several phytochemicals including fiber with potential phytopharmaceutical use. A study of 15 sunn hemp, Crotalaria juncea L., accessions demonstrated that total dietary fiber and protein content are significantly variable. As dietary fiber increases in the sunn hemp seed, protein decreases. Differences in total dietary fiber suggest that sufficient variability exists in this trait to allow enhancement in sunn hemp cultivars through plant breeding. [ABSTRACT FROM AUTHOR]

Increasing atmospheric CO2 concentration has led to concerns about potential effects on production agriculture as well as agriculture's role in sequestering C. In the fall of 1997, a study was initiated to compare the response of two crop management systems (conventional and conservation) to elevated CO2. The study used a split-plot design replicated three times with two management systems as main plots and two CO2 levels (ambient=375 μL L−1 and elevated CO2=683 μL L−1) as split-plots using open-top chambers on a Decatur silt loam (clayey, kaolinitic, thermic Rhodic Paleudults). The conventional system was a grain sorghum (Sorghum bicolor(L.) Moench.) and soybean (Glycine max(L.) Merr.) rotation with winter fallow and spring tillage practices. In the conservation system, sorghum and soybean were rotated and three cover crops were used (crimson clover (Trifolium incarnatumL.), sunn hemp (Crotalaria junceaL.), and wheat (Triticum aestivumL.)) under no-tillage practices. The effect of management on soil C and biomass responses over two cropping cycles (4 years) were evaluated. In the conservation system, cover crop residue (clover, sunn hemp, and wheat) was increased by elevated CO2, but CO2 effects on weed residue were variable in the conventional system. Elevated CO2 had a greater effect on increasing soybean residue as compared with sorghum, and grain yield increases were greater for soybean followed by wheat and sorghum. Differences in sorghum and soybean residue production within the different management systems were small and variable. Cumulative residue inputs were increased by elevated CO2 and conservation management. Greater inputs resulted in a substantial increase in soil C concentration at the 0–5 cm depth increment in the conservation system under CO2-enriched conditions. Smaller shifts in soil C were noted at greater depths (5–10 and 15–30 cm) because of management or CO2 level. Results suggest that with conservation management in an elevated CO2 environment, greater residue amounts could increase soil C storage as well as increase ground cover. [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]

Aims To find out how cannabis came to be subject to international narcotics legislation. Method Examination of the records of the 1925 League of Nations' Second Opium Conference, of the 1894 Report of the Indian Hemp Drugs Commission and other contemporary documents. Findings Although cannabis (Indian hemp) was not on the agenda of the Second Opium Conference, a claim by the Egyptian delegation that it was as dangerous as opium, and should therefore be subject to the same international controls, was supported by several other countries. No formal evidence was produced and conference delegates had not been briefed about cannabis. The only objections came from Britain and other colonial powers. They did not dispute the claim that cannabis was comparable to opium, but they did want to avoid a commitment to eliminating its use in their Asian and African territories. [ABSTRACT FROM AUTHOR]

In the seedlings of three cultivars of French bean (Phaseolns vulgaris), 'Prince', 'Masterpiece' and 'Pinto', co-infection by Sunn-hemp mosaic virus (SHMV) with either of the vascular wilt pathogens, Fusarium oxysporum f. sp. phaseoli (Fop) or f. sp. tracheiphilum (Fot) caused greater losses in total fresh weight and in leaf area compared with uninfected plants or plants infected singly with any one of these pathogens. Co-infection of a fourth cultivar ('Canadian Wonder') had no greater effects on growth reduction than single infection. The concentration of SHMV in the leaves of 'Prince' and to a greater extent in the leaves of 'Masterpiece' increased more after double infection than with infection by the virus alone. The nature and possible mechanisms of the pathogenic effects in French bean are discussed. [ABSTRACT FROM AUTHOR]

Cowpea mosaic virus was one of the viruses isolated from Crotalaria juncea showing mosaic, distortion and puckering symptoms. The virus induced local necrotic lesions in Canavalia ensiformis, Cassia occidentalis, Nicotiana debneyi, N. occidentalis, N. repanda and N. sylvestris and some cultivars of Phaseolus vulgaris 4-6 days after inoculation. It induced local chlorotic spots, which later became necrotic, as well as systemic chlorotic spots, vein chlorosis, distortion and puckering in Chenopodium amarantkolor. Sap from systemically infected cowpea cv. 'C20-55' was infective after dilution to 10"5 but not 10"*, after 10 min at 65°C but not 70°C, or after 4 days, but not 5. days, at a room temperature of 15-25 °C. Infectious virus was recovered from fresh reproductive tissues of infected cowpea cvs 'C20-55' and 'Ife Brown' plants but not after dehydration. [ABSTRACT FROM AUTHOR]

The growth of Crotalaria juncea L. and C. sericea Retz. under 8, 10, 12, 14 and 16 h daylengths was studied with respect to dry wt accumulation, leaf area increase, RGR, LAR, SLA, LWR, NAR, the value of α (ratio of mean relative growth rate to mean relative rate of leaf area increase) and S/R ratio. In both species, dry wt and leaf area increased up to 14 h daylength above which these features of C. juncea declined. The higher trend maintained in C. sericea suggests this is of selective value to a ruderal. C. sericea is characterized by a narrower range of values under the varying photoperiods. Strict comparison in terms of LAR is not possible owing to ontogenetic drift. In terms of RGR and NAR, C. sericea shows greater uniformity in all photoperiodic regimes. Values of α for this species also show a narrower range. All these are suggestive of its greater capacity than C. juncea to survive ecological vicissitudes in natural habitats. [ABSTRACT FROM AUTHOR]

Determines the suitability of late-summer-planted Tropic Sun sunn hemp as a green manure and cover crop for summer grain production system in warm temperate zones, as in the southeastern region of the United State. Sunn hemp biomass and nitrogen accumulation; Sunn hemp residue decomposition; Determination of nitrogen release from overwintered sunn hemp residue.

Reports on the natural occurrence of a begomovirus in sunn hemp, Crotalaria juncea, in India. Symptoms of the disease; Transmission of the sunn hemp virus by whiteflies; Polymerase chain reaction amplification of the sunn hemp virus' strong hybridization with a DNA-A probe of Indian tomato leaf curl virus.