• Authors:
    • Singer, J.
    • Moorman, T.
    • Cambardella, C.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 87
  • Issue: 3
  • Year: 2010
  • Summary: Coupling winter small grain cover crops (CC) with manure (M) application may increase retention of manure nitrogen (N) in corn ( Zea mays L.), -soybean [ Glycine max (L.) Merr], cropping systems. The objective of this research was to quantify soil N changes after application of liquid swine M ( Sus scrofa L.) at target N rates of 112, 224, and 336 kg N ha -1 with and without a CC. A winter rye ( Secale cereale L.)-oat ( Avena sativa L.) CC was established prior to fall M injection. Surface soil (0-20 cm) inorganic N concentrations were quantified every week for up to 6 weeks after M application in 2005 and 2006. Soil profile (0-120 cm in 5, 20-cm depth increments) inorganic N, total N, total organic carbon and bulk density were quantified for each depth increment in the fall before M application and before the CC was killed the following spring. Surface soil inorganic N on the day of application averaged 318 mg N kg -1soil in 2005 and 186 mg N kg -1soil in 2006 and stabilized at 150 mg N kg -1soil in both years by mid-November. Surface soil NO 3-N concentrations in the M band were more than 30 times higher in the fall of 2005 than in 2006. The CC reduced surface soil NO 3-N concentrations after manure application by 32% and 67% in mid- November 2005 and 2006, respectively. Manure applied at 224 kg N ha -1 without a CC had significantly more soil profile inorganic-N (480 kg N ha -1) in the spring after M application than manured soils with a CC for the 112 (298 kg N ha -1) and 224 (281 kg N ha -1) N rates, and equivalent inorganic N to the 336 (433 kg N ha -1) N rate. These results quantify the potential for cover crops to enhance manure N retention and reduce N leaching potential in farming systems utilizing manure.
  • Authors:
    • Dimitrova-Doneva, M.
    • Petkova, R.
  • Source: Agricultural Science and Technology
  • Volume: 2
  • Issue: 3
  • Year: 2010
  • Summary: A study has been conducted at the Experimental Station of Agriculture, Sredets to establish the effect of predecessor and mineral fertilization on chemical composition and energy value of wintering oats grain. The object of this study was wintering oat ( Avena sativa L) variety Jubile cultivated after predecessors (A): stubble (A 1), sorghum ( Sorghum vulgare Pers) - (A 2) and rape ( Brassica napus var. oleifera L) - (A 3) and fertilization, kg/ha - (B): N 40P 100K 50-B 1; N 80P 100K 50-B 2; N 120P 100K 50-B 3 and B 0-control N 0P 100K 50. The study covers chemical analysis of wintering oats grain made by Weende method. Calculations for the nutritive value of feed grain based on data obtained from chemical analysis were made (for ruminants) expressed in gross energy (GE) - MJ/kg dry substance, metabolizable energy (ME) - MJ/kg dry substance, feed units for milk (FUM, kg) and feed units for growth (FUG, kg) of dry substance - by using empirical equations. It was found that the predecessors stubble and rape increase the content of crude protein, crude fat and crude fibers in oats by 10.5 and 12.1%, 5.2 and 3.9%, 5.6 and 1.2%. The content of minerals and nitrogen-free extract (NFE) was the highest after predecessor sorghum. Increasing the doses of nitrogen fertilizer led to increasing the content of crude protein and fibers in grains on average by 14.4% and decreases the content of crude fats, ash and NFE by 7.0%, 3.2% and 3.4%, respectively. The differences in chemical composition of oat grains did not have a significant impact on its energy value expressed by GE, ME, (FUM) and (FUG).
  • Authors:
    • Miao, G.
    • Gao, Z.
    • Guo, C.
  • Source: Acta Agronomica Sinica
  • Volume: 36
  • Issue: 4
  • Year: 2010
  • Summary: Shading post flowering, caused by cloudy weather and the surrounding protective trees, often occurs in some wheat ( Triticum aestivum L.) area in north China. In general, wheat yield is negatively influenced by shading post flowering, but the effect on grain quality is reported discrepantly. This study aimed at disclosing the effects of post-flowering shading on photosynthesis of leaf and yield and quality of grain in wheat, accordingly, giving suggestions to wheat production. Three treatments were designed with shading of 20%, 50%, and 80% for 30 d, respectively. The normal condition was taken as the control. The results showed that shading treatments had significant influences on photosynthetic characteristics of flag leaf. The shading treatments increased the number of sterile spikelet and reduced the grain weight per spike and the 1000-grain weight. As a result, the grain yield of the three shading treatments significantly decreased by 27.6%, 49.0%, and 60.2% compared with the control. In the shading treatments, the contents of the chlorophylls a and b increased, whereas the ratio of chlorophyll a to chlorophyll b decreased. Moreover, the net photosynthetic rate, the stomatal conductance, and the transpiration rate were also significantly reduced, but the intercellular CO 2 concentration was promoted. The shading depression on net photosynthetic rate became smaller in the process of grain filling, with the largest effect at early stage of grain filling and the smallest effect at late stage of grain filling stage. The contents of protein, wet gluten, glutenin, gliadin and the ratio of glutenin to gliadin in grains increased significantly with the increase of shading. The shading influence on glutenin was greater than that on gliadin. Although the shading treatments decreased grain yield obviously, it raised some quality parameters, such as extensibility, development time, stability time, and water absorption of dough. The responses of yield and quality of wheat grain to shading were different because of the discrepant synthesis mechanisms of starch and protein under weak light condition. In wheat protective areas, yield is a priority factor and the tree-wheat intercropping mode should be avoided.
  • Authors:
    • Lajeunesse, J.
    • Pageau, D.
    • Reid, J. F.
    • Collin, J.
    • Vanasse, A.
    • Lanoie, N.
    • Durand, J.
  • Source: CROP SCIENCE
  • Volume: 50
  • Issue: 5
  • Year: 2010
  • Summary: Naked oat ( Avena sativa L.) grown in Quebec, Canada, produces an average of 10% covered grains. The objectives of this study were to evaluate the effects of environment, herbicide, and genotype on the proportion of covered grains, to study the relation between the presence of awns and the proportion of covered grains, and to determine the location of covered grains on the plant (tiller) and on the panicle. Eight oat lines were evaluated over 2 yr at four experimental sites. Each line was treated with bromoxynil/MCPA, dicamba/MCPA, or thifensulfuron methyl/tribenuron methyl applied at Zadoks 12-13 and compared to a hand-weeded check. The highest percentages of covered grains, 5.5 and 6.9%, were found at different sites in 2006 and 2007. The application of dicamba/MCPA increased the percentage of covered grains in the lines normally producing a higher proportion of covered grains, but low producing lines were less affected. Minor differences were found among the other weed control treatments. No relation was found between the presence of awns and the proportion of naked grains. Covered grains were mostly produced on the main stem and their position on the panicle depended on genotype and weed control treatment.
  • Authors:
    • Meinhardt, C. G.
    • Nelson, K. A.
    • Smoot, R. L.
  • Source: International Journal of Agronomy
  • Volume: 2010
  • Year: 2010
  • Summary: Field research (2003-2005) evaluated the effect of wheat row spacing (19 and 38 cm) and cultivar on double-cropped (DC) soybean response, 38-cm wheat on relay-intercrop (RI) response, and wheat cultivar selection on gross margins of these cropping systems. Narrow-row wheat increased grain yield 460 kg ha -1, light interception (LI) 7%, and leaf area index (LAI) 0.5 compared to wide rows, but did not affect DC soybean yield. High yielding wheat (P25R37) with greater LI and LAI produced lower (330 kg ha -1) soybean yields in an RI system than a low yielding cultivar (Ernie). Gross margins were $267 ha -1 greater when P25R37 was RI with H431 Intellicoat (ITC) soybean compared to Ernie. Gross margins were similar for monocrop H431 non-coated (NC) or ITC soybean, P25R37 in 19- or 38-cm rows with DC H431 NC soybean, and P25R37 in 38-cm rows with RI H431 ITC soybean in the absence of an early fall frost.
  • Authors:
    • Burdick, B.
    • Smoot, R.
    • Nelson, K.
  • Source: Crop Management
  • Issue: July
  • Year: 2010
  • Summary: Soybean seeded [ Glycine max (L.) Merr.] early into standing wheat ( Triticum aestivum L.) using relay intercropping (RI) and seed-coat technology may reduce mechanical damage and soybean interference to wheat. Field research at Novelty from 2003 to 2005 and Albany in 2004 evaluated effects of seed coat technology on wheat and soybean response, and gross profits of RI soybean using seed coat technology compared with selected full season (FS) wheat or soybean and double crop (DC) wheat-soybean. Wheat grain yield in the absence of soybean was 10 bu/acre greater in narrow (7.5-inch) than wide (15-inch) rows. Relay intercropped Intellicoat (ITC) treated 5143 soybean delayed germination and increased 15-inch wheat grain yields 8 bu/acre compared to non-coated (NC) 5143. At Novelty, RI 5143 ITC yield was similar in all three years and 7 bu/acre greater at Albany than 5143 NC. In 2005, dry conditions in mid- to late June reduced RI stands and yields compared to DC soybean at Novelty. Double-cropped 5143 NC soybean had greater gross profits than RI 5143 ITC when wheat and soybean prices were high. However, RI 5143 ITC gross profits were greater when soybean prices were high and wheat prices were low. The RI system using ITC maintained soybean yields and did not reduce wheat yields due to mechanical damage or soybean interference compared to non-coated or fungicide-only coating.
  • Authors:
    • Haar, M.
    • Lindquist, J.
    • Wortman, S.
    • Francis, C.
  • Source: Renewable Agriculture and Food Systems
  • Volume: 25
  • Issue: 4
  • Year: 2010
  • Summary: While weed management is consistently a top priority among farmers, there is also growing concern for the conservation of biodiversity. Maintaining diverse weed communities below bioeconomic thresholds may provide ecosystem services for the crop and the surrounding ecosystem. This study was conducted to determine if weed diversity, density and biomass differ within and among organic and conventional crop rotations. In 2007 and 2008, we sampled weed communities in four long-term crop rotations near Mead, Nebraska using seedbank analyses (elutriation and greenhouse emergence) and above-ground biomass sampling. Two conventional crop rotations consisted of a corn ( Zea mays) or sorghum ( Sorghum bicolor)-soybean ( Glycine max)-sorghum or corn-soybean sequence and a diversified corn or sorghum-sorghum or corn-soybean-wheat ( Triticum aestivum) sequence. Two organic rotations consisted of an animal manure-based soybean-corn or sorghum-soybean-wheat sequence and a green manure-based alfalfa ( Medicago sativa)-alfalfa-corn or sorghum-wheat sequence. Species diversity of the weed seedbank and the above-ground weed community, as determined by the Shannon diversity index, were greatest in the organic green manure rotation. Averaged across all sampling methods and years, the weed diversity index of the organic green manure rotation was 1.07, followed by the organic animal manure (0.78), diversified conventional (0.76) and conventional (0.66) rotations. The broadleaf weed seedbank density in the tillage layer of the organic animal manure rotation was 1.4*, 3.1* and 5.1* greater than the organic green manure, diversified conventional and conventional rotations, respectively. The grass weed seedbank density in the tillage layer of the organic green manure rotation was 2.0*, 6.1* and 6.4* greater than the organic animal manure, diversified conventional and conventional rotations, respectively. The above-ground weed biomass was generally greatest in the organic rotations. The broadleaf weed biomass in sorghum and wheat did not differ between organic and conventional rotations (CRs), but grass weed biomass was greater in organic compared to CRs for all crops. The above-ground weed biomass did not differ within CRs, and within organic rotations the grass weed biomass was generally greatest in the organic green manure rotation. The weed seedbank and above-ground weed communities that have accumulated in these rotations throughout the experiment suggest a need for greater management in long-term organic rotations that primarily include annual crops. However, results suggest that including a perennial forage crop in organic rotations may reduce broadleaf weed seedbank populations and increase weed diversity.
  • Authors:
    • Prasad, V.
    • Staggenborg, S.
    • Assefa, Y.
  • Source: Crop Management
  • Issue: November
  • Year: 2010
  • Summary: Because sorghum is a drought-tolerant crop, it is often preferred by producers in cases of expected water stress. The objectives of this review were to summarize the water requirements, effect of water stress, and hybrid variation in drought tolerance of grain sorghum, and to suggest possible solutions that could help narrow the gap between potential and actual dryland sorghum yield. We reviewed more than 70 reports in peer-reviewed journals, extension publications, books, and websites. Grain sorghum tolerates and avoids drought more than many other cereal crops, but the drought response of sorghum does not come without a yield loss. Water stress at the vegetative stage alone can reduce yield more than 36%, and water stress at the reproductive stage can reduce yield more than 55%. Eighty percent of sorghum production in the world is under dryland conditions. We deduced that by focusing on techniques that can improve water availability in sorghum growing season alone, we can double the current dryland sorghum yield with the existing genetic potential. Results of this review suggest the existence of genotypic variation in drought tolerance among sorghum hybrids due to possible physiological differences or vice versa. We concluded by presenting possible management options to reduce the effects of water stress in dryland conditions and suggesting possible areas of research.
  • Authors:
    • Hao, M.
    • Fan, J.
    • Malhi, S.
  • Source: Canadian Journal of Soil Science
  • Volume: 90
  • Issue: 3
  • Year: 2010
  • Summary: Nitrate (NO 3-) leaching and water contamination have become a worldwide concern. In this review, some examples are presented to show the extent and magnitude of NO 3- accumulation in the soil profiles and its potential effects on contamination of ground water and surface water under dryland farming in northern China. Climatic and management factors affecting NO 3- leaching are also discussed. In northern China, rainfall is relatively sparse, but the high intensity of precipitation and porous soils play an important role in the accumulation of NO 3N in soil and its subsequent leaching in the soil profile. There is a risk of nitrate accumulation and leaching when high rates of fertilizer N are applied to improve crop yields, and it becomes even worse when conventional land use is changed from cereal crops to vegetable crops and fruit orchards. Under such conditions, shallow ground water might be polluted by NO 3-. This suggests that more attention should be paid to prevent this problem by using best management practices, especially by controlling the amount of N fertilizer input, balanced fertilization, split N application, inclusion of crops with deep taproots in the rotation and minimizing summer fallow (especially tilled) frequency.
  • Authors:
    • Park, S. W.
    • Lee, H. P.
    • Sung, C. H.
    • Lee, S. B.
    • Jang, T. I.
  • Source: Paddy and Water Environment
  • Volume: 8
  • Issue: 3
  • Year: 2010
  • Summary: This article describes the pilot study on the water reuse for agricultural irrigation in Korea. The project is a part of the application of wastewater reuse system for Agriculture project, a 21st Century Frontier R&D Program sponsored by the Ministry of Education, Science, and Technology and associated with the Sustainable Water Resources Research Program. The goal of the project was to develop infra-technologies necessary to reclaim wastewater for irrigation in agriculture. The project involved two phases: laboratory and field research. Reclamation techniques for irrigation and feasible reuse were developed as a first step in proposing appropriate water quality standards. Reclaimed wastewater of various qualities was used to irrigate cereal crops and vegetables, and possible adverse effects on crops, humans, and the environment were investigated. The optimal reclamation methods required to satisfy water quality standards were explored and the operational characteristics investigated. Moreover, an inventory of farmlands that could reuse reclaimed wastewater was established. Feasible delivery systems for irrigation were developed, and pilot project sites were identified. Finally, operational field data from pilot units were collected and analyzed. This research and development may help solve water shortage problems in Korea, which left unaddressed will have an adverse effect on future generations.