Bharat P. Singh

Agricultural Management Practices to Sustain Crop Yields and Improve Soil and Environmental Qualities

In the past several decades, agricultural management practices consisting of intensive tillage and high rate of fertilization to improve crop yields have resulted in the degradation of soil and environmental qualities by increasing erosion and nutrient leaching in the groundwater and releasing greenhouses gases, such as carbon dioxide (CO2) and nitrous oxide (N2O), that cause global warming in the atmosphere by oxidation of soil organic matter. Consequently, management practices that sustain crop yields and improve soil and environmental qualities are needed. This paper reviews the findings of the effects of tillage practices, cover crops, and nitrogen (N) fertilization rates on crop yields, soil organic carbon (C) and N concentrations, and nitrate (NO3)-N leaching from the soil. Studies indicate that conservation tillage, such as no-till or reduced till, can increase soil organic C and N concentrations at 0- to 20-cm depth by as much as 7–17% in 8 years compared with conventional tillage without significantly altering crop yields. Similarly, cover cropping and 80–180 kg N ha year fertilization can increase soil organic C and N concentrations by as much as 4–12% compared with no cover cropping or N fertilization by increasing plant biomass and amount of C and N inputs to the soil. Reduced till, cover cropping, and decreased rate of N fertilization can reduce soil N leaching compared with conventional till, no cover cropping, and full rate of N fertilization. Management practices consisting of combinations of conservation tillage, mixture of legume and nonlegume cover crops, and reduced rate of N fertilization have the potentials for sustaining crop yields, increasing soil C and N storage, and reducing soil N leaching, thereby helping to improve soil and water qualities. Economical and social analyses of such practices are needed to find whether they are cost effective and acceptable to the farmers.

Torrefaction of sorghum biomass to improve fuel properties

Torrefaction of energy sorghum and sweet sorghum bagasse was investigated at three different temperatures (250, 275 & 300°C) for 30min to determine product yields and its compositions. The torrefied solid yield ranged from 43% to 65% for sweet sorghum bagasse and 51-70% for energy sorghum. The energy density of both torrefied sorghums increased between 1.6 and 1.4 folds. Besides water, the acetic acid, with a maximum yield of 101.90gL-1 was the dominant compound in the aqueous fraction of liquid products. The aqueous fraction from sweet sorghum bagasse contained furfural and furan carboxyl aldehydes, while ketones and alcohols were dominant from energy sorghum as other key compounds. Phenolic type chemicals and furan derivatives were the major compounds in the oil fraction of the liquid product, accounted up to 58wt%. The condensable liquid products can be further upgraded into high-value platform chemicals.

Pearl millet genome sequence provides a resource to improve agronomic traits in arid environments

Pearl millet [Cenchrus americanus (L.) Morrone] is a staple food for more than 90 million farmers in arid and semi-arid regions of sub-Saharan Africa, India and South Asia. We report the ∼1.79 Gb draft whole genome sequence of reference genotype Tift 23D2B1-P1-P5, which contains an estimated 38,579 genes. We highlight the substantial enrichment for wax biosynthesis genes, which may contribute to heat and drought tolerance in this crop. We resequenced and analyzed 994 pearl millet lines, enabling insights into population structure, genetic diversity and domestication. We use these resequencing data to establish marker trait associations for genomic selection, to define heterotic pools, and to predict hybrid performance. We believe that these resources should empower researchers and breeders to improve this important staple crop.

Livestock Improve Household Food Security and Sustainability of Ethiopian Small Farms

ABSTRACT The role of livestock in determining the socio-economic status, food security and sustainability of smallholder mixed farms was studied during 1999 and 2000 in the Harar Highlands of Eastern Ethiopia. Community level information on farm households was collected using semi-structured interviews, key informant interviews, and field observations. A well-being instrument was developed on the basis of community level data to rank the households into poor, medium, and well-to-do categories. Detailed characterization of the households in the three groups was carried out by an in-depth case study of individual farms followed by a wider scale formal survey. Community level interviews revealed that smallholders considered meeting household food requirements and maintaining soil fertility of farm plots most important for farm sustainability. The energy content of the food consumed by a farm family and the soil humus balance of annually cropped plots were used as proxy indicators for household food balance and soil fertility, respectively. Case study revealed that medium and well-to-do were high in household energy adequacy levels and positive in humus balance in annually cropped plots. Livestock accounted for 27% of the total household energy supply. In contrast, food supply in the poor category was 15% below the adequacy level and the field humus balance was negative. Poor had minimal livestock holding and livestock contributed only 2% of the total household energy supply. Results from the farm survey were similar to the case study. Medium and well-to-do had positive household food balance (180 ± 20.6%, and 186 ± 17.8%, respectively) and humus balance (385 kg/ha and 360 kg/ha, respectively) while poor had deficit household food balance (65 ± 15.8%) and negative soil humus balance (2365 kg/ha). The contribution of livestock to total household energy supply varied significantly (P ≤ 0.01) with the farm category, and accounted for 3.1 (0–5.7%), 23 ± 6.8% and 17 ± 7.9% of the total in the poor, medium and well-to-do, respectively. The results suggest that farms with less than one Tropical Livestock Units are not sustainable in the Harar Highlands of Eastern Ethiopia. Therefore, any agricultural development initiative in Ethiopia must include both crop and animal components for success.

Development of a High-Density Linkage Map and Tagging Leaf Spot Resistance in Pearl Millet Using Genotyping-by-Sequencing Markers

Pearl millet [Pennisetum glaucum (L.) R. Br; also Cenchrus americanus (L.) Morrone] is an important forage and grain crop in many parts of the world but genomic resources for this species are needed to facilitate crop improvement. The reference genetic map developed using 150 recombinant inbred lines contained 16,650 single‐nucleotide polymorphisms and 333,567 sequence tags spread across all seven chromosomes. This map is the densest yet reported for this crop and will be a valuable resource for the pearl millet community. Genome mapping studies are a prerequisite for tagging agronomically important traits. Genotyping‐by‐sequencing markers can be used to build high‐density linkage maps, even in species lacking a reference genome.

Soil carbon and nitrogen pools under long-term productivity of rhizoma peanut and perennial weeds management systems

Abstract The effects of a 10-year-old rhizoma peanut (RP) (Arachis glabrata Benth.), a perennial legume forage, and perennial weeds (PW) management systems on soil organic C (SOC), total N (STN), NH4-N, NO3-N, potential C and N mineralization (PCM and PNM), microbial biomass C and N (MBC and MBN), and particulate organic C and N (POC and PON) were evaluated in a Norfolk loamy fine sand (fine-loamy, siliceous, thermic Typic Kandiudult) in 2000 and 2001 in Georgia, USA. Aboveground biomass yield and N accumulation increased from June to October in 2000 and 2001, were greater in RP than in PW from July to October, and were greater in 2000 than in 2001 in RP. Root length density increased from June to September, and was greater in RP than in PW in September. The SOC, STN, POC, PON, MBC, MBN, PCM, and PNM varied seasonally but in different trends than those of biomass yield and root length density. In contrast, soil NH4-N in 2001 and NO3-N contents in 2000 and 2001 increased from June to September similar to those of biomass yield and N accumulation. Averaged across sampling dates, SOC, STN, POC, PON, MBC, MBN, PCM, PNM, and NO3-N were greater in RP than in PW and greater in 2000 than in 2001. Short-term productivity of RP may enrich soil mineral N by supplying N from above- and belowground residues and long-term productivity may improve soil quality and productivity by increasing microbial activities, N mineralization, and C and N sequestrations compared with PW.

Cover Crops for Enriching Soil Carbon and Nitrogen Under Bioenergy Sorghum

Soil carbon (C) and nitrogen (N) can be enriched with cover crops under agronomic crops, but little is known about their enrichment under bioenergy crops. Legume (hairy vetch [Vicia villosa Roth]), nonlegume (rye [Secale cereale L.]), a mixture of legume and nonlegume (hairy vetch and rye), and a control with no cover crop were grown in the winter to evaluate their effects on soil organic C (SOC), total N (STN), and nitrate-N (NO3-N) contents under bioenergy Sorghum from 2010 to 2013. Cover crop biomass and C and N contents were greater with vetch/rye mixture than rye and the control. The SOC at 5–15 and 15–30 cm was greater with vetch/rye than other treatments under forage Sorghum and at 0–5 cm and 5–15 cm was greater with vetch/rye and vetch than rye or the control under sweet Sorghum. The STN at 5–15 cm was greater with vetch/rye and the control than rye under forage Sorghum and at 0–5 and 5–15 cm was greater with vetch/rye and rye than the control under sweet Sorghum. Both SOC and STN at all depths increased linearly from 2010 to 2013, regardless of cover crops and Sorghum species. The NO3-N content at all depths varied with cover crops from 2011 to 2013. Bicultural cover crops, such as hairy vetch/rye mixture, have greater potential to sequester C and N than monocultures, such as hairy vetch and rye, or no cover crop due to greater crop residue returned to the soil under bioenergy Sorghum where aboveground biomass is harvested for bioenergy or feedstock.

Soil Carbon and Nitrogen in Response to Perennial Bioenergy Grass, Cover Crop and Nitrogen Fertilization

Abstract Cover crop and nitrogen (N) fertilization may maintain soil organic matter under bioenergy perennial grass where removal of aboveground biomass for feedstock to produce cellulosic ethanol can reduce soil quality. We evaluated the effects of cover crops and N fertilization rates on soil organic carbon (C) (SOC), total N (STN), ammonium N (NH 4 -N), and nitrate N (NO 3 -N) contents at the 0–5, 5–15, and 15–30 cm depths under perennial bioenergy grass from 2010 to 2014 in the southeastern USA. Treatments included unbalanced combinations of perennial bioenergy grass, energy cane ( Saccharum spontaneum L.) or elephant grass ( Pennisetum purpureum Schumach.), cover crop, crimson clover ( Trifolium incarnatum L.), and N fertilization rates (0, 100, and 200 kg N ha −1 ). Cover crop biomass and C and N contents were greater in the treatment of energy cane with cover crop and 100 kg N ha −1 than in the treatment of energy cane and elephant grass. The SOC and STN contents at 0–5 and 5–15 cm were 9%–20% greater in the treatments of elephant grass with cover crop and with or without 100 kg N ha −1 than in most of the other treatments. The soil NO 3 -N content at 0–5 cm was 31%–45% greater in the treatment of energy cane with cover crop and 100 kg N ha −1 than in most of the other treatments. The SOC sequestration increased from 0.1 to 1.0 Mg C ha −1 year −1 and the STN sequestration from 0.03 to 0.11 Mg N ha −1 year −1 from 2010 to 2014 for various treatments and depths. In contrast, the soil NH 4 -N and NO 3 -N contents varied among treatments, depths, and years. Soil C and N storages can be enriched and residual NO 3 -N content can be reduced by using elephant grass with cover crop and with or without N fertilization at a moderate rate.

Insect Incidence and Damage on Pearl Millet (Pennisetum glaucum) Under Various Nitrogen Regimes in Alabama

Abstract Although pearl millet [Pennisetum glaucum (L.) R. Br.; Poales: Poaceae] is grown extensively on 5 continents and is attacked by various insects at all stages of growth and development, little is specifically known of how yields of this important crop are affected by insect herbivory. This study was conducted in north central Alabama to determine insect occurrence on pearl millet and to determine the levels of damage caused by insects feeding on pearl millet genotypes at different nitrogen rates. The field experiment was laid out following a randomized complete block design with 4 replications in which 4 genotypes and 4 fertilizer levels were arranged in factorial combinations. The pearl millet genotypes consisted of 2 open pollinated lines, ‘2304’ and ‘LHBO8’, and 2 hybrids, ‘606A1*2304’ and ‘707A1*4280’ and fertilization rates used were 0, 40, 80 and 120 kg ha-1 N. Insect samplings were carried out weekly from 61 to 109 days after planting (DAP). Insects in 6 orders and 11 families were found on pearl millet genotypes. Eastern leaf-footed stinkbug (Leptoglossus phyllopus (L.); Hemiptera: Coreidae) was the most prevalent and dominant insect species found followed by the American bird grasshopper (Schistocerca americana Drury; Orthoptera: Acrididae) and the differential grasshopper (Melanoplus differentialis (Thomas: Orthoptera: Acrididae). Population of L. phyllopus was at its peak during the latter part of the growing season from 81 to 109 DAP. Populations of S. americana and M. differentialis declined as crop matured (61 DAP > 66 DAP >75 DAP). Results also showed that leaf and head damage did not differ among genotypes and nitrogen rates tested.