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Ensuring food and nutritional security in light of high climate variability and a rapidly growing population remains a challenge. Mungbean (Vigna radiata (L.) Wilczek) is a short duration, drought-tolerant, and ureide-exporting legume crop capable of symbiotic atmospheric nitrogen fixation. Estimates of biological N2 fixation by mungbean in different soil textures have not been extensively studied. We conducted this study to evaluate plant growth and N2 fixation of five mungbean genotypes (Berken, 8735, IC 8972-1, STB#122, 223) inoculated with Bradyrhizobium spp. and grown on loamy sand and silt loam soils under glasshouse conditions. Mungbean dry matter yield, δ15N values, shoot content, amounts of N-fixed, and soil N uptake were all higher on the silt loam soil compared to the loamy sand soil, demonstrating the effects of soil properties on plant growth and N2 fixation potential. Among genotypes, IC 8972-1 produced the highest biomass (7.85 g plant−1), shoot N content (200 mg plant−1), and soil N uptake (155 mg plant−1) than other genotypes. The significant interaction between soil texture and genotypes for root dry matter and %Ndfa indicates the major role of legume root-nodule bacteria in symbiotic N2 fixation. This study demonstrated that N2 fixation in mungbean is affected by both genotypes and soil properties, illustrating the need to consider soil properties in order to maximize N contribution from mungbean to agricultural production systems.

Current understanding of the effects of tillage systems on cotton growth and development of contemporary varieties is limited for producers of the Upper Southeast Coastal Plain of the United States. Tillage studies were conducted in Suffolk, VA, from 2013 to 2016 evaluating conventional, minimal, no-tillage, and strip-tillage systems on early season growth, soil compaction, and lint yield of four contemporary varieties using a split-plot design. Soil compaction was greatest in the no-till system with yearly depths to a root restrictive layer ranging from 8–26 cm. No-till resulted in shorter plant heights compared to other tillage methods in 2 out of 4 yr. Relative yield for no-till was 0.78, an 8% reduction compared to the other tillage systems. Deltapine 1321 B2RF was consistently taller than other varieties in all years; with significant varietal differences being present during all sampling intervals each year except 2013. Fibermax 1944 GLB2 was shorter than other varieties. In-season plant development was affected more by variety than tillage. Lint yield differed among varieties in 2013, 2014, and 2016. Deltapine 1321 B2RF produced the highest lint yields of 1746 kg ha⁻¹, 1467 kg ha⁻¹, and 693 kg ha⁻¹ in 2013, 2014, and 2015, respectively. Differences in lint quality parameters were influenced more by variety than tillage system. In the short term there was no significant growth or yield penalty associated with no-till cotton production as compared to other tillage systems. Variety selection and environment were the most important factors contributing to cotton yield during this four year study.

Located within the Sahel region, Senegal faces several agricultural production challenges. Limited rainfall, poor soil fertility, and insufficient agronomic inputs all contribute to low pearl millet [Pennisetum glaucum (L.) R. Br.] yields. This study was initiated to assess the potential for increasing millet yields through intercropping (living cover) and mulching (desiccated cover) practices. During the 2013 and 2014 growing seasons, pearl millet was intercropped with cowpea [Vigna unguiculata (L.) Walp.], mungbean [Vigna radiata (L.) Wilczek], or grown under mulch (neem [Azadirachta indica] leaves applied at 2 t ha–1). Field trials were conducted at two sites within Senegal’s central millet– peanut (Arachis hypogaea L.) basin, in Bambey (14°41¢382 N, 16°28¢122 W) and iés (14°45¢452 N, 16°53¢142 W). Soil moisture and plant N (based on the normalized difference vegetation index [NDVI]) were measured in addition to yield. When inter- cropped with a legume, millet grain yields increased up to 55% compared to millet alone. The combined grain yields under inter-cropping (millet + legume) were always higher than yields of millet alone, up to 67% in Bambey. Mulching increased soil moisture up to 14%, with yield increases of up to 70% over millet with no mulch. Plant N increased in both intercropped and mulched millet, with NDVI increases up to 21% with mulch and 16% when grown with a legume (prior to flowering). These yield increases were achieved using resources that are available and affordable to small-scale producers in the region (seeds and mulch), and did not require the addition of fertilizer input. Published version

This work examines N use by switchgrass (Panicum virgatum L.). A study was conducted on two well-established ‘Cave-in-Rock’ switchgrass stands in Blacksburg (37° 11′ N, 80° 25′ W) and Orange (38° 13′ N, 78° 07′ W) Virginia, USA. Plots were fertilized in 2001 (year 1) with 0, 90, 180, or 270 kg N per hectare. No additional N was applied in 2002 (year 2) and 2003 (year 3), and biomass was harvested in July and November for years 2 and 3 (but only in November of year 1). Root and soil samples were collected in May, July, September, and November each year and analyzed for N. Nitrogen fertilization did not increase yields in 2001 (year 1), but it did provide residual benefits in 2002 (year 2) and 2003 (year 3). Root-N levels at 15 cm depth increased with fertilization, fluctuated seasonally between roots and shoots, and root-N was reduced over the course of the study. With two harvests per year, about 100 kg N hectare per year were removed in biomass, even in plots with no N added—suggesting N already present in the soils (at 15 cm depth) contributed to yields; but the soil mineral-N pools were reduced by the end of year 3. Nitrogen-use efficiency, apparent N recovery, and partial factor productivity were reduced with higher N applications. The data support the notion that biomass production can be achieved with minimal N inputs, but stands must be managed to maintain that N reserve over the long term. There is also a need to quantify the N pool to depths greater than 15 cm in other agro-ecoregions.

Many livestock producers minimize input costs by relying solely on naturalized, mixed-species pasture, but expose themselves to risks associated with forage yields that fluctuate in response to variable environmental conditions. This study was undertaken to assess winter triticale (xTriticosecale spp.) as a potential component of forage systems from the perspective of reducing forage yield risk. Triticale was sown each month from May until October in replicated plots for five consecutive years. Monthly harvests of triticale and mixed-pasture plots were made through October during the year of establishment and in April and May the following spring. Monte Carlo simulation modeled differences between triticale and mixed pasture yields for each planting month and harvest month combination. The models predicted that triticale yields in August (June planted) and October (August planted) should exceed mixed pasture yields by averages of 0.62 ± 0.32 (mean ± standard deviation) and 0.77 ± 0.52 Mg ha -1 , respectively. Yields of triticale planted in July or later and harvested in the following spring were also predicted to exceed mixed pasture by 0.50 ±0.21 Mg ha -1 for July planted/April harvest to 1.33 ± 0.32 Mg ha -1 for September planted/April harvest. Risk analysis produced probabilities of benefit from incorporating triticale into forage systems, thus generating more meaningful results than conventional ANOVA.

In developing management strategies for hemipteran pests in cotton (Gossypium hirsutum L.), it is important to understand the potential of plants to compensate for loss of the fruiting structures. Because of its northern latitude, Virginia has fewer available heat units relative to other cotton-producing states. Therefore, there may be limited opportunity for compensation relative to more southerly production areas. Previous work in Virginia demonstrated that cotton can sustain relatively high levels of first position square loss with no yield loss. This study evaluated the impact of a single event loss of 10–14-d-old bolls via mechanical removal on cotton lint yields with the premise that boll loss would have greater impact than square loss as less time and fewer heat units are available for compensation. Field experiments examining four levels of boll removal (0, 5,15 and 20%) were conducted in 2001,2002 and 2003. Each boll removal level was imposed at three different dates, beginning 2 wks after first flower and at 3- to 5-d intervals thereafter. Yields ranged from 1103–1422 in 2001, 909–1124 in 2002, and 843–1015 kg lint per ha in 2003. There were no significant differences in lint yields among the boll removal dates or removal levels. The results of our study showed that cotton in Virginia, which approaches the northernmost latitude for cotton production, is capable of sustaining losses as high as 20% of 10–14-d-old bolls at a single removal event without affecting lint yield. Results were consistent despite the wide variation in rainfall and temperatures during the 3 study years.

Cotton (Gossypium hirutum) yields in the Virginia Coastal Plain are often reduced by restricted root growth due to acid subsoils and hardpans, and sandy soils with low water‐holding capacity. The objective of this experiment was to determine if subsoiling or subsoiling and subsoil lime placement affected nutrient element uptake, root growth and penetration, and plant development on selected Coastal Plain soils. Treatments were (i) untreated check, (ii) simulated subsoiled to 61 cm, and (iii) simulated subsoiled to 61 cm and 1 t ha‐1 of lime applied to the subsoiled trench. Cores 30.5 cm in diameter and 81 cm deep were collected in the field and placed in the greenhouse. The cotton cultivar DP50 was grown on these soils cores for 90 days. Rooting depth and taproot length were measured and approximate total root length was determined by the line intersect method. Root dry matter weight increased (p