Crotalaria Juncea Research Articles

EFFECT OF COVER CROPS ON SOIL ATTRIBUTES, PLANT NUTRITION, AND IRRIGATED TROPICAL RICE YIELD

ABSTRACT In flood plains, cover crops are able to alter soil properties and significantly affect rice nutrition and yield. The aims of this study were to determine soil properties, plant nutrition, and yield of tropical rice cultivated on flood plains after cover crop cultivation with conventional tillage (CT) and no-tillage system (NTS) at low and high nitrogen (N) fertilization levels. The experimental design was a randomized block in a split-split-plot scheme with four replications. In the main plots were cover crops [sunhemp (Crotalaria juncea and C. spectabilis), velvet bean (Mucuna aterrima), jackbean (Canavalia ensiformis), pigeon pea (Cajanus cajan), Japanese radish (Raphanus sativus), cowpea (Vigna unguiculata)] and a fallow field. In the subplots were the tillage systems (CT or NTS). The nitrogen fertilization levels in the sub-subplots were (10 kg N ha-1 and 45 kg N ha-1). All cover crops except Japanese radish significantly increased mineral soil nitrogen and nitrate concentrations. Sunhemp, velvet bean, and cowpea significantly increased soil ammonium content. The NTS provides higher mineral nitrogen and ammonium content than that by CT. Overall, cover crops provided higher levels of nutrients to rice plants in NTS than in CT. Cover crops provide greater yield than fallow treatments. Rice yield was higher in NTS than in CT, and greater at a higher rather than lower nitrogen fertilization level.

Doses of Crotalaria juncea: Residual effect on zucchini and maize crop in sequence to broccoli

ABSTRACT Amounts of N from green manures not absorbed in the first cycle can be absorbed by the subsequent crops. Therefore, it is important to quantify and monitor the residual effects of green manure to increase the agronomic benefits of its use in cropping systems. Our purpose was to study the residual effect of doses of the Crotalaria juncea green manure applied in broccoli crop in the zucchini-maize succession. This study was carried out in a crop succession system organized in three crops, with seven treatments and four major doses of green manure as 0, 3, 6, and 9 t ha-1. The control treatments consisted of a mineral fertilization, a treatment with 25 t ha-1 compost, and another as absolute control without organic compost or mineral fertilizer. The experimental plot consisted of five rows spaced 0.8 m with 3 m in length. The experimental design was a completely randomized block with four replications in a split-plot scheme in time for growth with variables of adjustment of statistical models by the response surface methodology. With the highest dose of green manure, the yield of zucchini plants was greater than the yield with 25 t ha-1 compost control and similar with mineral fertilizer. As for the maize yield in the dose of 9 t ha-1 green manure, the yield was superior only to absolute control. There was a residual effect of C. juncea mass, which was applied in broccoli crop for growth and yield of zucchini and maize grown in succession. The residual effect is dependent on the amount of weight of C. juncea applied, with the greatest effects in larger doses.

English

No-tillage is an agricultural system that is proposed as a sustainable soil management system. This paper aims to evaluate the short-term effects of cover crops on a no-tillage system, by assessing a number of physical and chemical attributes of soil of the Brazilian Amazon region. The experiment was carried out in a typical Ferralsol under a no-tillage system from March to December, 2014. A randomized block design, with four replicates was used. The performance and effects of fourteen cover crops (Cajanus cajan, Canavalia ensiformis, Crotalaria juncea, Crotalaria ochroleuca, Crotalaria spectabilis, Stizolobium aterrima, Stizolobium cinereum, Pennisetum glaucum, Sorghum bicolor, Sorghum sudanense, Urochloa brizanha cv. Xaraes, Urochloa brizantha cv. Piata and Urochloa ruziziensis and Zea mays) and fallow (control treatment) on the soil quality were assessed. The cover crops were sown in the off season in April 2014, before the summer crop (maize). The levels of P, K, Ca2+, Mg2+, Al3+, H+Al, saturation by aluminum, sum of bases, organic matter, pH and resistance to soil penetration were evaluated following the end of the cover crops growth. Some near-surface soil attributes were affected by the cover crops. Urochloa species improved the levels of potassium in the soil at depths up to 5 cm below the surface. The highest penetration resistance was observed in the superficial layer between 12 and 16 cm deep, with penetration resistance values varying between 2472 and 2912 kPa. The Urochloa exhibited satisfactory agronomic performance when grown under a simulated crop livestock integration system. It is concluded that the use of cover crops in a no-till system has the potential to improve the chemical quality of soil in the Southwestern Amazon region. Key words: No-tillage, ecological intensification, sustainability, Rondonia, green manure.

Nitrate leaching in soybean rotations without nitrogen fertilizer

Nitrate leaching is a primary pathway of nitrogen loss from agricultural systems, and is affected by both tillage and cropped species. However, there is little information on conservation systems without nitrogen fertilization. Nitrate leaching was assessed in soybean (Glycine max) cropped in rotation with the following cover crops under no-till and chiseling: ruzigrass (Brachiaria ruziziensis), grain sorghum (Sorghum bicolor), pearl millet (Pennisetum glaucum), forage sorghum (Sorghum bicolor), Sunn hemp (Crotalaria juncea), triticale (X Triticosecale) and sunflower (Helianthus annuus). Ruzigrass and grain sorghum cropped in the fall/winter resulted in similar NO3 − leaching, which was greater under sunflower than under triticale, likely due to high N uptake and immobilization in plant residues. Sunn hemp as a spring crop resulted in higher NO3 − leaching than pearl millet at two locations and forage sorghum at one location likely due to a higher N input by biological fixation. Millet resulted in the lowest N leaching by depleting the soil solution. Chiseling/fallow resulted in higher nitrogen leaching as compared with non-fixing N cover crops. Even when N is not applied, it is important to intensify cropping systems in tropical environments using cover crops with vigorous root systems and high N demand, which prevent N leaching, as well as provides N to the following crop as the straw is mineralized.

Improvement of biomass and essential oil production of Lippia alba (Mill) N.E. Brown with green manures in succession

The objective of this work was to evaluate the biomass production, yield and composition of essential oil from Lippia alba (Mill) N.E. Brown, cultivated in succession with green manures. The experiment was conducted in the field with five treatments: T1 – sunn hemp (Crotalaria juncea L.); T2 – velvet-bean (Mucuna aterrima Holland); T3 – cowpea (Vigna unguiculata L. Walp); T4 – spontaneous plants; and T5 – control. Lippia alba essential oils were chemically characterized by gas-chromatography with mass spectrometry detector (GC/MS) at two harvest moments (120 and 262days after transplantation). The application of green manures, mainly velvet-bean, increased biomass and essential oil production, mainly in the second harvest (total oil yield of 62.43Lha−1). The main volatile compounds identified in the essential oil (β-myrcene, germacrene D, limonene, and carvone) didn’t suffer significant changes in function of the treatment applied. However, all the compounds mentioned report a higher yield in L. alba plants cultivated with velvet-bean (except germacrene D). Compared to control treatment, β-myrcene, limonene, and carvone increased 1.3%, 4.2%, and 6.6% with velvet-bean.The use of velvet-bean as green manure is a cheap resource that causes a positive effect in the cultivation of L. alba plants and may reduce the use of chemical fertilizers, being an eco-friendly strategy for the cultivation of medicinal plants.

The Potential of Green Manure Mixtures to Provide Nutrients to a Subsequent Lettuce Crop

ABSTRACTThe objectives of this greenhouse experiment were to quantify the benefits of green manure (GM) diversity and to assess effect of GM on a succeeding lettuce crop. Species included barley (B), field pea (P), sunn hemp (S), and buckwheat (U). Treatments included single plantings of B and P and mixtures of B and P (BP), B, P, and S (BPS), and B, P, S, and U (BPSU). The pea GM had the highest shoot concentration of potassium, calcium, magnesium, manganese, zinc, and iron. Roots had higher concentrations of nutrients than shoots. Accumulation of nutrients in legumes was higher than in barley. The CO2 flux from the soil suggests that the most intensive mineralization period occurred within two weeks after incorporation of GMs. The mixtures and single planting of P mixtures had a significant benefit over single planting of B regarding fresh and dry weight of the lettuce.

Application of different cover crops and mineral fertilizer doses for no-till cultivation of broccoli, cauliflower and cabbage

No-till practices have not been widely adopted by vegetable producers due to the necessity of seedbed preparation to incorporate organic fertilizers and plant residues of the preceding crops. This study evaluated biomass yield and residue decomposition of different cover crops, and their influence on agronomic performance of Brassica crops cultivated under no-till system. The experiment was laid out in randomized complete blocks with 4 x 3 factorial treatment combinations of four cover crops: Sunn hemp (SH), Signal grass (SG), Pearl millet (PM), and SH + PM mixture, and three doses of mineral fertilizer-0, 50, and 100% of the recommended fertilizer doses for broccoli. The same design and treatments were used for cauliflower and then for cabbage, separately.. The experiment was carried out with 4 repetitions on parcels of 20 m2. No beds were raised, for the planting of seedlings was done in pits. The following agronomic traits were evaluated: Dry biomass (DB) and decomposition of cover crop residues (DR), and the number of leaves (NL), height (H), fresh head weight (FHW) and dry head weight (DHW), and yield (Y) of Brassica crops. The highest DB occurred in treatments with SH (Give value). SG presented the highest DR constant and the shortest half-life of residues in this study.; Broccoli presented better agronomic performance when cultivated on residues containing SH.; Fertilizer doses influenced broccoli and cabbage productivity, which were the highest for the treatment with 100% dose of mineral fertilizer.

Leguminosas isoladas e consorciadas com milheto em diferentes sistemas de manejo do solo no feijão orgânico.

Vários estudos têm demonstrado as vantagens da utilização de plantas de cobertura em manter ou melhorar a qualidade do solo e produtividade da cultura. No entanto, os efeitos dessa gestão em feijão comum orgânico em condições de savana, ainda são desconhecidos. Este estudo teve como objetivo avaliar o efeito de leguminosas, mucuna (Mucuna pruriens (L.) DC, feijão guandu (Cajanus cajan L.) HUTH, feijão de porco (Canavalia ensiformis), crotalária (Crotalária juncea) em monocultura e em consórcio com milheto (Pennisetum glaucum L.) R. Br. de 1810, na produção de grãos no feijoeiro comum em sistema orgânico de produção sob o sistema do manejo do solo convencional e plantio direto. O experimento foi realizado com a cultivar BRS Pontal, em um delineamento em blocos casualizados. Aos 90 dias após a germinação das plantas de feijão foram avaliadas, o número de vagens por planta (NVP), número de grãos por vagem (NGV), número de grãos por planta (NGP) , peso de 100 grãos (M100G) e produção de grãos. Os resultados mostraram que o número de vagens, número de grãos e produtividade do feijoeiro no sistema orgânico, foram influenciados pelas culturas de cobertura do solo e sistemas manejo do solo, com destaque para mucuna associados com milheto e sistema de plantio direto, que proporcionou o melhor desempenho destes parâmetros. A maior produção de grãos foi observado com a mucuna associados com milho em sistema de plantio direto. A produtividade média de grãos orgânicos foi de 3.8 Mg ha-1. A análise de agrupamento mostrou um efeito marcante de sistemas de manejo do solo sobre os componentes de produção do feijoeiro.

Growth, Yield and Seed Quality of Sunnhemp (Crotalaria juncea L.) as Influenced by Foliar Nutrition and Pinching

Growth, Yield and Seed Quality of Sunnhemp (Crotalaria juncea L.) as Influenced by Foliar Nutrition and Pinching

Growth models for morphological traits of sunn hemp

The objective of the present study was to fit Gompertz and Logistic nonlinear to descriptions of morphological traits of sunn hemp. Two uniformity trials were conducted and the crops received identical treatment in all experimental area. Sunn hemp seeds were sown in rows 0.5 m apart with a plant density of 20 plants per row meter in a usable area of 52 m × 50 m. The following morphological traits were evaluated: plant height (PH), number of leaves (NL), stem diameter (SD), and root length (RL). These traits were assessed daily during two sowing periods—seeds were sown on October 22, 2014 (first period) and December 3, 2014 (second period). Four plants were randomly collected daily, beginning 7 days after first period and 13 days after for second period, totaling 94 and 76 evaluation days, respectively. For Gompertz models the equation was used y=a*e^((?-e?^((b-c*xi))and Logistic models the equation was used yi= a/(1+e^((-b-c*xi)). The inflection points of the Gompertz and Logistic models were calculated and the goodness of fit was quantified using the adjusted coefficient of determination, Akaike information criterion, standard deviation of residuals, mean absolute deviation, mean absolute percentage error, and mean prediction error. Differences were observed between the Gompertz and Logistic models and between the experimental periods in the parameter estimate for all morphological traits measured. Satisfactory growth curve fittings were achieved for plant height, number of leaves, and stem diameter in both models using the evaluation criteria: coefficient of determination (R²), Akaike information criterion (AIC), standard deviation of residuals (SDR), mean absolute deviation (MAD), mean absolute percentage error (MAPE), and mean prediction error (MPE).

Type 3 Secretion System (T3SS) of Bradyrhizobium sp. DOA9 and Its Roles in Legume Symbiosis and Rice Endophytic Association.

The Bradyrhizobium sp. DOA9 strain isolated from a paddy field has the ability to nodulate a wide spectrum of legumes. Unlike other bradyrhizobia, this strain has a symbiotic plasmid harboring nod, nif, and type 3 secretion system (T3SS) genes. This T3SS cluster contains all the genes necessary for the formation of the secretory apparatus and the transcriptional activator (TtsI), which is preceded by a nod-box motif. An in silico search predicted 14 effectors putatively translocated by this T3SS machinery. In this study, we explored the role of the T3SS in the symbiotic performance of DOA9 by evaluating the ability of a T3SS mutant (ΩrhcN) to nodulate legumes belonging to Dalbergioid, Millettioid, and Genistoid tribes. Among the nine species tested, four (Arachis hypogea, Vigna radiata, Crotalaria juncea, and Macroptilium atropurpureum) responded positively to the rhcN mutation (ranging from suppression of plant defense reactions, an increase in the number of nodules and a dramatic improvement in nodule development and infection), one (Stylosanthes hamata) responded negatively (fewer nodules and less nitrogen fixation) and four species (Aeschynomene americana, Aeschynomene afraspera, Indigofera tinctoria, and Desmodium tortuosum) displayed no phenotype. We also tested the role of the T3SS in the ability of the DOA9 strain to endophytically colonize rice roots, but detected no effect of the T3SS mutation, in contrast to what was previously reported in the Bradyrhizobium SUTN9-2 strain. Taken together, these data indicate that DOA9 contains a functional T3SS that interferes with the ability of the strain to interact symbiotically with legumes but not with rice.

Carbon stocks in oxisols under agriculture and forest in the southern Amazon of Brazil

We evaluated the initial effects of different agricultural management systems on carbon stocks in Oxisols in the southern Amazon and compared them to the adjacent native forest. Four management systems in a commercial area of grain production (soybeans in monoculture, summer soybeans with corn and Panicum milaceum as second crop, summer soybeans with corn and Urochloa brizantha as second crop, and summer soybeans with U. brizantha+Crotalaria juncea) were evaluated in a completely randomized design with five repetitions. It was found with removal of native vegetation and introduction of annual crops that there was a reduction of 30% (−8.1Mgha−1) in soil C stocks with the traditional management system of soybean monoculture/second crop corn. However, it is possible to maintain C stocks at levels comparable to the native vegetation with soy cultivation in summer and cover crops U. brizantha+C. juncea as second crop. With this strategy, there was storage of 0.2 and 0.12Mgha−1 C-CO2 per year at depths of 0–0.1m and 0.1–0.2m, respectively. In soybean monoculture/corn there was C-CO2 emission of 6.45 and 2.09Mgha−1yr−1 at depths of 0–0.1m and 0.1–0.2m, respectively. These results suggest that the practices traditionally used in commercial agricultural areas may not be sufficient to maintain C stocks in Amazon soil compared to the native vegetation. Therefore, large-scale management for low green-house gas emission (C-friendly agriculture) in the Amazon must be rethought and alternative strategies, such as rotation with pastures (e.g. integrated crop-livestock systems), should be adopted in order to preserve and/or increase C stocks, reducing the impact of CO2 emissions into the atmosphere.

Effects of strip-tilled cover cropping on the population density of thrips and predatory insects in a cucurbit agroecosystem

Strip-till cover cropping provides a structurally complex habitat (both diverse above ground vegetation and modified soil surface environment) in subsequent crops, which can contribute to suppressing herbivores in the cash crop, through either enhancing conservation biological control or altering herbivore behavior to the complex habitat. Two field trials (spring and autumn) were conducted to examine effects of strip-tilled cover crops (sunn hemp and marigold) on population densities of thrips (primarily, Frankliniella occidentalis and Thrips palmi) and generalist predators (Orius spp. and ground beetles, Aephnidius spp.) in cucurbit plantings. The results showed that strip-tilled cover crop treatments reduced thrips densities on cucurbit crops compared to the conventional monoculture. The strip-tilled treatments suppressed thrips densities more consistently in the autumn than in the spring trial. The reduced densities of thrips in strip-tilled cover crop plots were not attributable to the enhanced activity of predatory insects, but were most likely due to the disruption of host locating ability of thrips. Our study showed that the strip-till cover cropping could be an effective pest management technique for sustainable cucurbit production.

Development of rapid and highly sensitive detection of Bean common mosaic necrosis virus in leguminous crops using loop-mediated isothermal amplification assay

Bean common mosaic necrosis virus (BCMNV) is a plant pathogenic virus that can infect leguminous crops such as kidney beans, sunn hemp, red beans, and mung beans. BCMNV has not been reported in Korea and is classified as a quarantine plant virus. Currently, the standard diagnostic method for diagnosis of BCMNV is reverse transcription (RT)-nested PCR system. However a more rapid monitoring system is needed to enable the testing of more samples. The use of highly efficient loop-mediated isothermal amplification (LAMP) assay for its detection has not yet been reported, and development of LAMP for detecting BCMNV in this study. In addition, confirmation of LAMP amplification can be achieved using restriction enzyme Mse I (T/TAA). The developed technique could be used for more rapid, specific and sensitive monitoring of BCMNV in leguminous crops than conventional nested RT-PCR.

Leaf area estimation from linear measurements in different ages of Crotalaria juncea plants.

The goal of this study was to estimate the leaf area of Crotalaria juncea according to the linear dimensions of leaves from different ages. Two experiments were conducted with C. juncea cultivar IAC-KR1, in the 2014/2015 sowing seasons. At 59, 82, 102, 129 days after sowing (DAS) of the first and 61, 80, 92, 104 DAS of the second experiment, 500 leaves were collected, totaling 4,000 leaves. In each leaf, the linear dimensions were measured (length, width, length/width ratio and length × width product) and the specific leaf area was determined through Digimizer and Sigma Scan Pro software, after scanning images. Then, 3,200 leaves were randomly separated to generate mathematical models of leaf area (Y) in function of linear dimension (x), and 800 leaves for the models validation. In C. juncea, the leaf areas determined by Digimizer and Sigma Scan Pro software are identical. The estimation models of leaf area as a function of length × width product showed superior adjustments to those obtained based on the evaluation of only one linear dimension. The linear model Ŷ=0.7390x (R2=0.9849) of the real leaf area (Y) as a function of length × width product (x) is adequate to estimate the C. juncea leaf area.

PERANAN BAHAN ORGANIK Chromolaena odorata DAN Crotalaria juncea DALAM MENINGKATKAN KETERSEDIAAN HARA FOSFOR BAGI PERTUMBUHAN TANAMAN KEDELAI DI LAHAN KERING

The development of soybean crops in dry land are often confronted with low soil fertility which causes be hampered growth and crop production. T he efforts to manage soil fertility with application of fertilizer chemical also did not have much effect, because the soil buffering capacity is low which causes the fertilizer is given can be leached out or bound by other elements (especially elements P), so that P can not be absorbed by plants, while P is an element plants need in large quantities. This study aims to improve the availability of nutrients phosphate for renewed growth in soybean crops in dry land. This study aims to improve the availability of nutrients phosphate for renewed growth in soybean crops in dry land. This study was designed with a completely randomized design, factorial of two factors. The first factor is the kind of organic material consisting of four levels ie: without any organic material, organic material from plants Chromolaena odorata, organic material from plants Crotalaria juncea and organic matter from manure. The second factor is P fertilization that consists of two levels, namely: 50 kg-36.ha SP-1 and SP-36.ha 100 kg-1. The results showed that the organic matter C. odorata and C. juncea with P fertilization can improve nutrient availability in the soil P, P nutrient uptake by soybean plants also increased with organic matter C. odorata and C. juncea accompanied fertilization P.

Levels of Crotalaria juncea on growth, production, recovery and efficiency of the use of N in broccoli

ABSTRACT The recommendation for green manure (GM) in cropping systems still has little scientific support, with few studies addressing the effects of nutrient amounts from green manure on the growth and production of the crop. Our aim was to evaluate the effect of levels of Crotalaria juncea green manure on the growth, production, and efficiency of the use as well as the apparent recovery of N in broccoli crop. Seven treatments were established; the main with four doses of green manure: 0, 3, 6, and 9 t/ha on a dry matter (DM) basis, applied with 12 t/ha compost. The control treatments consisted of mineral fertilization, the treatment with 25 t/ha compost, and another as the absolute control. Comparatively, production under the absolute control was less than all other treatments with green manure doses and application of 12 t/ha compost. The production of plants grown with 25 t/ha compost was superior to that of plants grown with dose of 0 t/ha and similar to that obtained with 3 t/ha; however, it was inferior to those produced with doses of 6 and 9 t/ha green manure. The highest percentage of N recovered (REC N) by the broccoli plants was observed close to a dose of 3 t/ha green manure, with a maximum point of 37.90% (2.8 t/ha), while in larger doses of 6 and 9 t/ha showed estimated values of 31.91% and 20.49%, respectively. The physiological efficiency of the use of N (EFUN) showed an effect similar to apparent recovery of N (REC N), with higher EFUN from lowest to highest dose of green manure, that is, 3, 6, and 9 t/ha, with estimated values of 70.41, 62.45, and 26.02 g DM per g of N uptake, respectively. The mass amounts of applied C. juncea influenced positively on the growth and productivity of broccoli. The lower mass of applied green manure increases the physiological efficiency of the use of N with more apparent recovery of the applied N.

Effect of seven years of nutrient supplementation through organic and inorganic sources on productivity, soil and water conservation, and soil fertility changes of maize-wheat rotation in north-western Indian Himalayas

Sloping croplands require different nutrient management practices than levelled lands in order to check soil degradation. In order to check erosion vis-a vis degradation, fertilization of maize (Zea mays L.)-wheat (Triticum aestivum L. emend Fiori & Paol.) crop rotation with organic manure supplemented with inorganic fertilizer is required. A seven year fixed plot field experiment under rainfed conditions was conducted comprising seven management practices in both maize and wheat crops: control (0), 100% NPK through inorganic fertilizers (100-0), 100% N through farmyard manure (FYM) (0–100), substitution of 50% N through four different organic manures viz., FYM (50 + 50 FYM), vermicompost (50 + 50 VC), poultry manure (50 + 50 PM) and in-situ green manuring (50 + 50 GM) of sunnhemp (Crotalaria juncea L.). Crop productivity, runoff coefficient, soil loss, and post harvest soil fertility parameters were assessed to estimate the effects of combined use of inorganic and organic sources of nutrients. The results indicated that 50 + 50 (FYM) could maintain significantly higher (p < 0.05) productivity of maize (18–74%) and wheat (10–77%) than 100-0 in different years. However, 50 + 50 (GM) resulted in higher reduction of runoff (16–40%) and soil loss (13–50%) than 100-0 in different years, leading to higher conservation of natural resources. Maize grain yield was significantly negatively correlated with run-off (r2 = 0.16 with p = 0.005) and soil loss (r2 = 0.26 with p = 0.0001). Our study concluded that combined use of chemical fertilizers and organic manures particularly FYM or GM may be considered as a feasible and environment-friendly option for soil conservation.

Biomass and nitrogen content of fifteen annual warm-season legumes grown in a semi-arid environment

Warm-season legumes can provide a low-input feedstock for biofuel, but research comparing the biomass and N content is lacking. The objective of this experiment was to evaluate and compare 15 annual, warm-season legumes in semi-arid climates as biomass feedstocks. A factorial randomized complete block design field experiment with four replications was conducted at sites near Beeville and Stephenville, TX, during the 2010 and 2011 growing seasons with an average 450 mm total rainfall and irrigation. Whole plot (1.5 m × 6 m; 25 cm row spacing) was legume species and subplot (1.5 m × 3 m) treatments included harvest every 30 d (initiated at first flower or canopy closure, whichever occurred first) or harvest once at the end of the season or plant death, whichever occurred first. ‘Kauffman’ and ‘Tropic Sunn’ (Crotalaria juncea L.) produced an average 8650 kg ha−1 and was the most consistent across environments. ‘Iron & Clay’ and ‘Red Ripper’ cowpeas (Vigna unguiculata (L.) Walp.; 4700 kg ha−1), and ‘Rio Verde’ and ‘Tecomate’ lablab (Lablab purpureus (L.) Sweet; 4000 kg ha−1), generally yielded less biomass than crotalaria. Because of their consistent biomass yields Iron & Clay cowpea, Red Ripper cowpea cut repeatedly through the growing season as well as Rio Verde and Tecomate lablab, or pigeonpea cut at the end of season are suitable biomass options for these and similar environments. Further experiments are needed to determine the potential role of these legumes as crop rotation, cover crop, or integrated livestock-bioenergy uses for biomass production.

Hydrophysical Quality of an Oxisol Under a No-tillage System with Alternative Crops to Renew a Sugarcane Field

Maintaining crop residues on the surface of soils with the possibility of renewing sugarcane fields could be a key factor for improving the structural quality of the soil. The objective of the present study was to assess the structural quality of soil after the use of alternative crops under a no-tillage system in the restoration of a sugarcane field, by the least-limiting water range (LLWR) and the load-bearing capacity (LBC) models. The study utilized a randomized block design in a banded scheme, with six treatments and five replications. Two soil depths were evaluated: 0.15 and 0.25 m. The five crops studied were Crotalaria juncea, C. ochroleuca, Helianthus annuus (sunflower), Glycine max (L.) Merrill (soybean), and Sorghum bicolor (L.) Moench (sorghum), in addition to a fallow treatment. The highest LBC values in the 0.15 m depth were provided by the treatment grouping of soybean–sorghum until the water content reached 0.26 m3 m−3; after this value, the highest LBC values were provided by the C. ochroleuca–C. juncea–sunflower–soybean treatment grouping. In the 0.25 m depth, the highest LBC values were provided by the C. juncea–sunflower–sorghum treatment grouping until the water content reached 0.26 m3 m−3; after this value, the highest LBC values were provided by the fallow–soybean grouping for water content reaching 0.50 m3 m−3. The crops used prior to sugarcane planting modified the physical and water properties of the soil at the two depths evaluated.