Green and sweet corn grown under different cover crops and phases of the no-tillage system

ABSTRACT Special corn is cultivated all year conventionally round; however, its productivity increases when grown under a no-tillage system (NTS). This study aimed to evaluate the agronomic performance of sweet and green corn cultivated under residues of different cover crops and the NTS implantation stages. Two experiments were carried out in the randomized block design, with four replications, in each of the three areas. The experiments consisted of evaluating the sweet and green corn, simultaneously, in three areas at different stages of development of NTS: initial (1 year), transition (7 years), and consolidation (19 years) with six types of cover crops: Signal grass (SG), Pearl millet (PM), Sunn hemp (SH), a mixture of SG + SH, SG + PM, and PM + SH. The dry matter (DM) production of the cover crops, the productivity of husked and unhusked ears, straw, and grain yield were evaluated. The SH had the highest dry mass production among the studied cover crops in all phases of the NTS. The phase of the NTS did not influence the productivity of ears with or without husk in green corn. The cultivation of sweet corn in transition and consolidation areas of the NTS showed better yields when compared to the initial phase of the system.

Areawide management of fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae), using selected cover crop plants

Background Fall armyworm, Spodoptera frugiperda (J. E. Smith) is a migratory moth that annually migrates northward each spring from sites in southern Florida and southern Texas. This caterpillar pest feeds on and damages row, turf and vegetable crops in the eastern and central U.S. Before migrating in spring, it feeds on cover crops in central and eastern Florida and expands its populations. Our objective was to use multi-year studies to compare fall armyworm populations that develop in cover crop plants. Methods A series of field experiments and a laboratory feeding study were conducted to compare infestation and feeding and of fall armyworm on different cover crop plants. Field experiments had plots planted with corn (Zea mays L.), sorghum-sudangrass [Sorghum bicolor (L.) Moench], a standard cover crop in Florida, and two alternative cover crops, sunn hemp (Crotalaria juncea L.) and cowpea [Vigna unguiculata (L.) Walpers spp. unguiculata]. Another trial compared populations in sorghum-sudangrass and in mixtures of sorghum-sudangrass with buckwheat (Fagopyrum esculentum Moench) or pearl millet (Cenchrus americanus (L.) Morrone). Fall armyworm larvae were fed and allowed to develop on different sunn hemp germplasm in a laboratory trial. Results Field populations of fall armyworm were highest on corn, followed by sorghum-sudangrass. Sunn hemp and cowpea had larval populations 70–96% less than on sorghum-sudangrass, suggesting replacement of this cover crop with either plant species might help reduce areawide populations of resident or migratory fall armyworm. Larvae collected from cover crop plots had parasitism levels that averaged 30%, with Chelonus insularis (Hymenoptera: Braconidae) emerging as the most commonly-collected species. Larval feeding on different sunn hemp germplasm lines resulted in no difference in weight gain. Conclusions Replacing sorghum-sudangrass with sunn hemp varieties or germplasm should be acceptable as a replacement cover crop for areawide management of fall armyworm.

Soil Respiration and Carbon Balance Under Cover Crop in a no-Till Tropical Fruit Orchard

Agricultural practices, specifically crop and land management schemes, greatly influence the ability of soil to produce CO2 under varying conditions. A 2-year research study was planned to quantify carbon-dioxide (CO2) emission fluxes and total C (TC) contribution in a no-till tropical soil under carambola with sunn hemp-velvet bean cover cropping (CC) systems. Composted poultry manure (PM) was applied as an additional N source. The treatments were fallow control (F), fallow with PM (FM), sunn hemp (SH), SH with PM (SHM), velvet bean (VB), and VB with PM (VBM). Average daily CO2 emission from VB was 23 and 15% higher than control and SH plots, respectively, during CC growing season. Similarly, CO2 emission after CC termination was highest from VB plots. About 17% higher CO2-C emission was observed from manure applied plots which indicates that additional food sources stimulated microbial activity in the soils and subsequently produced more CO2. However, total C contribution in SH plots were significantly higher than in VB plots and was more apparent when manure was not applied. Soil and air temperature played key roles in CO2 emission, specifically during the CC growing season. Considering both input and output parameters of C in the soil, our results suggest that SH has the better potential in reducing CO2 emission and accumulating more C in the soil than VB in tropical fruit orchard.

Improving Quality of Sunn Hemp (Crotalaria Juncea L.) Foliage as Roughage Source for Ruminants by using Microorganisms

This study aims to investigate the chemical composition, fermentation characteristics, and in vitro ruminal digestibility efficiency of Sunn hemp silage with Fermented juice of epiphytic lactic acid bacteria (FJLAB) and bacillus subtilis. The experiment was designed in a CRD. Five dietary treatments were fresh Sunn hemp (FS, the positive control), Sunn hemp silage (SS, the negative control), Sunn hemp silage with B. subtilis (SSB), Sunn hemp silage with FJLAB (SSL), and SSB plus FJLAB (SSBL). The results showed the OM content of Sunn hemp silage was decreased (p < 0.05), but fiber contents (NDF, ADF, cellulose, and hemicellulose) were increased when compared with fresh Sunn hemp. However, SSL and SSBL could improve nutrition values (higher CP Reduction efficiency; p < 0.01, decrease cellulose; p < 0.01, and hemicellulose content; p < 0.10) and quality grading of Sunn hemp silage when compare with the negative control which did not affect to CP and EE values. Furthermore, FJLAB reduced fiber content and increase CP content of Sunn hemp silage, whereas B. subtilis presented the opposite results. However, the combination of FJLAB and B. subtilis showed the best treatment of Sunn hemp silage of this experiment (the highest CP and EE Reduction efficiency, ruminal gas production, and organic matter degradability; OMD). HIGHLIGHTS Pyrrolizidine Alkaloids, a toxin associated with disease in ruminants, found in Sunn hemp is completely destroyed by anaerobic microorganisms of silage The fermentation process of silage was improved by increasing lactic acid production and decreasing pH value to inhibit the growth of undesirable microbes Combination of fermented juice of epiphytic lactic acid bacteria (FJLAB) and Bacillus subtilis, lactic acid producer, for Sunn hemp silage treatment yielded the highest lactic acid production and nutritive values GRAPHICAL ABSTRACT

Effect of Cover Crops Associated With Lettuce Production Under No-Tillage System

The use of cover crops has benefits for the chemical, physical and biological properties of the soil. However, together with the need for good vegetable productivity, considerable challenges arise in several regions of Brazil. The preparation of conventional soil for initiating no-tillage systems is necessary to create a management history and assimilate the benefits of the no-tillage system in vegetables, ensuring sustainable production. The objective of this research was to evaluate lettuce yield as a function of different cover crops as a function of resistance to soil penetration. The experiment was conducted in the horticulture sector of the University of Rio Verde, Rio Verde, Goi&aacute;s, Brazil. The cover crops used were sunflower (Helianthus annuus), sunn hemp (Crotalaria juncea), and fallow, and the vegetable used was lettuce (Lactuca sativa). The variables analyzed were plant height and lettuce yield, straw decomposition, and soil resistance to penetration. The collected data were submitted to analysis of variance, and if significant, was compared by Tukey test (p &lt; 0.05) and regression analysis. The lettuce height in the different management systems showed no statistical differences. The decomposition of the straw presented accentuated degradation for the evaluated cover crops and the productivity was bigger in the straw of crotalaria and fallow. Soil resistance for cover crops was not greater than 2 MPa.

SURFACE RESIDUES: EFFECTS ON SOIL MOISTURE AND TEMPERATURE1

ABSTRACT This study aimed to determine how crop residue placement and composition would affect soil water content and temperature during the dry season in the central region of Espírito Santo state, Brazil. A 19-week field study was conducted from April to August 2017. A 2 x 4 factorial study with four replications was implemented using a randomized complete block design. Factors were soil management [conventional tillage (CT) and no soil disturbance (ND)] and residue amendment [maize (Zea mays L.), sunn hemp (Crotalaria juncea L.), a maize-sunn hemp mixture, and a no amendment control]. Soil water content and temperature were measured weekly at predetermined soil depth intervals. Soil water content was higher in ND plots amended with surface residues than under all other treatments in the 0 to 0.05 m depth range. All residue amendments in this range were equally effective in conserving soil water. Surface residues reduced soil temperature by up to 8.4 °C relative to the control in ND plots. Incorporating residue amendments by CT cancelled all temperature-moderating benefits provided by surface residues. These results indicate that surface residues from cereals, legumes, or cereal/legume mixtures are equally effective in conserving soil water and moderating soil temperature during the dry season. Additional research is needed to determine how improved soil environmental conditions, generated by surface residues, would affect nutrient acquisition and crop performance.

Successive crops of broccoli, green corn and pea after taro (Colocasia esculenta)-sunn hemp (Crotalaria juncea) consortium

Aiming to assess the residual effect of the biomass of the taro-sunn hemp consortium on the performance of the successive crops of broccoli, green corn and peas, an experiment, with 11 treatments, corresponding to the cutting of Crotalaria juncea in the taro-sunn hemp consortium (55, 70, 85, 100, 115, 130, 145, 160, 190 and 220 days after sowing - DAS) plus a control treatment (Colocasia esculenta), was performed. Soil samples were collected and chemical analysis was performed before crop establishment. Plant characteristics and productivity of broccoli, green corn and pea pods were assessed. There were no major changes in soil chemical composition. Higher values of inflorescence fresh matter and broccoli yield were observed in the treatments in which cuts of Crotalaria juncea occurred 145 DAS. The residual effect of Crotalaria juncea cuttings provided higher corn plants and a greater fresh matter of spikes with straw and productivity of commercial ears, compared to the control. There was no residual effect on the characteristics evaluated for pea. The residual effect of Crotalaria juncea cropped in a consortium with Colocasia esculenta increases broccoli yield when cut from 145 DAS and corn cropped in succession.

Winter Malting Barley Growth, Yield, and Quality following Leguminous Cover Crops in the Northeast United States

There is growing interest in malting barley (Hordeum vulgare L.) production in the Northeastern United States. This crop must meet high quality standards for malting but can command a high price if these quality thresholds are met. A two-year field experiment was conducted from 2015 to 2017 to evaluate the impact of two leguminous cover crops, sunn hemp (Crotalaria juncea L.) and crimson clover (Trifolium incarnatum L.), on subsequent winter malting barley production. Four cover crop treatments—sunn hemp (SH), crimson clover (CC), sunn hemp and crimson clover mixture (SH + CC), and no cover crop (NC)—were grown before planting barley at three seeding rates (300, 350, and 400 seeds m−2). SH and SH + CC produced significantly more biomass and residual nitrogen than the CC and NC treatments. Higher barley seeding rates led to higher seedling density and winter survival. However, the subsequent spring and summer barley growth metrics, yield, and malting quality were not different in any of the treatments. There is much left to investigate in determining the best malting barley production practices in the Northeastern United States, but these results show that winter malting barley can be successfully integrated into crop rotations with leguminous plants without negative impacts on barley growth, yield, and grain quality.

Quality properties of sunn hemp (Crotalaria juncea L.) and maize (Zea mays L.) silages

Maize is an ideal forage crop for ensilage because of its high levels of fermentable carbohydrates, although it is low in protein. Sunn hemp is a legume with a high crude protein content with potential to be used in combination with maize to provide a silage with a higher protein content. Different percentages of sunn hemp-maize mixtures of 80-20, 60-40, 40-60 and 20-80 respectively were compared to silages of sole maize and sunn hemp. In the laboratory study, DLG classifications (color, smell, structure, total score and quality class), silage loss (%), silage pH, dry matter content, flieg score, crude protein content, crude ash content, NDF, ADF, metabolic energy (MJ kg-1 DM), dry matter intake, percent digestible dry matter and relative feed value were determined at the end of 60 days ensilage. The crude protein contents of silages increased as the sunn hemp ratio in the mixtures increased. In addition, pure sunn hemp silage and mixtures, especially 80% sunn hemp mixed with 20% maize, were found suitable for silage and it was concluded that sunn hemp and sunn hemp-maize silage mixtures could be used in animal husbandry.

Rhizobial adhesives enhance nodule formation in sunn hemp

ABSTRACTInoculation of legume seed with rhizobacteria before planting is an efficient and convenient way of introducing effective rhizobacteria to soil vicinity of legume root and ensuring nitrogen fixation in cover cropped field. However, there are still challenges in identifying the proper seed coating technique to ensure microbial survival in adverse environmental conditions and maintaining the symbiotic relation with plants. The objectives of this study are firstly, to analyze the effectiveness of different sticking agents aiding inoculation of Bradyrhizobium japonicum L. in sunn hemp seeds to enhance root nodule formation. Secondly, to observe nodulation pattern over time as affected by the treatment and lastly to check if there is significant difference between main root and lateral root nodulation pattern due to the treatments. Two similar field studies were conducted in fall 2019 and summer 2020 using four sticking agents: water, peanut oil, 10% jaggery solution, and 40% gum arabic solution. The fall study showed no significant differences among total nodules across treatments, but percentage of active nodules was highest in the oil treatment and lowest in the water treatment. In the summer study, significantly higher total nodules were seen in the jaggery treatment and the lowest was in water treatment again, however, there were no differences in percentage of total active nodules across treatments. Interestingly, the trend across weeks showed gum arabic treatment exhibiting higher main root nodulation and jaggery treatment exhibiting higher lateral root nodulation. Overall, water as an adhesive was less effective in aiding nodulation compared to other treatments. Peanut oil and jaggery showed better performance as adhesives aiding active nodulation and could be more effective than gum arabic or water.