• Authors:
    • Smith, D.
    • Yang, W.
    • Chen, X.
    • Liu, W.
    • Zhang, J.
  • Source: African Journal of Agricultural Research
  • Volume: 6
  • Issue: 27
  • Year: 2011
  • Summary: Production practice shows shaded soybean in wheat-maize-soybean; relay strip intercropping system has better tolerance to drought as compared with sole cropping soybean. Our researches are to understand the reasons through non-hydraulic root signals (nHRS), yield and the relationships among them. Pot experiments were conducted with two soybean cultivars, under shade of maize (LI) and normal irradiance (HI). nHRS were traced during manipulative progressive soil drying period at branching stage under good soil conditions (HW), water stress treatment (LW), in 2010. Well-watered (WW), light drought (LD), moderate drought (MD) and severe drought (SD) were applied in 2009. In response to soil drying, nHRS appeared earlier in Gongxuan No.1 (GX) than Gongqiudou 05-8 (GQ) under two irradiance treatments, but it disappeared earlier for GX than GQ under normal irradiance. GX exhibited a wider average soil water content threshold range (TR) of nHRS under low irradiance. Drought stress significantly decreased the shoot dry mass, root mass and grain yield (P
  • Authors:
    • Garcia, F.
    • Garcia, A.
    • Ernst, O.
    • Cano, J.
    • Bordoli, M.
    • Beux, L.
    • Bautes, C.
    • Barbazan, M.
    • Quincke, A.
  • Source: Agrociencia (Montevideo)
  • Volume: 15
  • Issue: 2
  • Year: 2011
  • Summary: The objectives of this study were to summarize the recent information generated in the country related to the potassium fertilization and find a tentative critical level of Potassium (K) in soil for various crops in Uruguay, using the most widely used K soil test. The data come from 50 K-response experiments in barley, wheat, corn, soybeans, sorghum, and sunflower, conducted by different working groups from 2004 to 2010, in soils with different texture and exchangeable K levels. The fertilizer rates ranged from 0 to 240 kg/ha of K 2O and in all cases the source of K was broadcasted KCl at planting date. Potassium fertilizer increased crop yield in 15 of 50 sites (Pr
  • Authors:
    • Fiorin, J.
    • Nicoloso, R.
    • Tornquist, C.
    • Amado, T.
    • Campos, B.
  • Source: Revista Brasileira de Ciencia do Solo
  • Volume: 35
  • Issue: 3
  • Year: 2011
  • Summary: Soil C-CO 2 emissions are sensitive indicators of management system impacts on soil organic matter (SOM). The main soil C-CO 2 sources at the soil-plant interface are the decomposition of crop residues, SOM turnover, and respiration of roots and soil biota. The objectives of this study were to evaluate the impacts of tillage and cropping systems on long-term soil C-CO 2 emissions and their relationship with carbon (C) mineralization of crop residues. A long-term experiment was conducted in a Red Oxisol in Cruz Alta, RS, Brazil, with subtropical climate Cfa (Koppen classification), mean annual precipitation of 1,774 mm and mean annual temperature of 19.2degreesC. Treatments consisted of two tillage systems: (a) conventional tillage (CT) and (b) no tillage (NT) in combination with three cropping systems: (a) R0 - monoculture system (soybean/wheat), (b) R1 - winter crop rotation (soybean/wheat/soybean/black oat), and (c) R2 - intensive crop rotation (soybean/black oat/soybean/black oat+common vetch/maize/oilseed radish/wheat). The soil C-CO 2 efflux was measured every 14 days for two years (48 measurements), by trapping the CO 2 in an alkaline solution. The soil gravimetric moisture in the 0-0.05 m layer was determined concomitantly with the C-CO 2 efflux measurements. The crop residue C mineralization was evaluated with the mesh-bag method, with sampling 14, 28, 56, 84, 112, and 140 days after the beginning of the evaluation period for C measurements. Four C conservation indexes were used to assess the relation between C-CO 2 efflux and soil C stock and its compartments. The crop residue C mineralization fit an exponential model in time. For black oat, wheat and maize residues, C mineralization was higher in CT than NT, while for soybean it was similar. Soil moisture was higher in NT than CT, mainly in the second year of evaluation. There was no difference in tillage systems for annual average C-CO 2 emissions, but in some individual evaluations, differences between tillage systems were noticed for C-CO 2 evolution. Soil C-CO 2 effluxes followed a bi-modal pattern, with peaks in October/November and February/March. The highest emission was recorded in the summer and the lowest in the winter. The C-CO 2 effluxes were weakly correlated to air temperature and not correlated to soil moisture. Based on the soil C conservation indexes investigated, NT associated to intensive crop rotation was more C conserving than CT with monoculture.
  • Authors:
    • Dimitrijevic-Brankovic, S.
    • Siler-Marinkovic, S.
    • Djordjevic, T.
  • Source: International Journal of Food Properties
  • Volume: 14
  • Issue: 1
  • Year: 2011
  • Summary: The antioxidant activities and total phenolic content of 4 cereals (buckwheat, wheat germ, barley, and rye) and 4 legume seeds (lentils, mungo bean, red kidney bean, and soy bean) were determined. The total phenolic content (TPC), determined according to the Folin-Ciocalteu method, for cereal samples varied from 13.2 to 50.7 mg Gallic acid equivalent/g of dried extract, while for legume samples varied from 17.0 to 21.9 mg Gallic acid equivalent/g of dried extract. Antioxidant activities were comparatively assessed by 2,2-diphenyl-1- picrylhydrazyl (DPPH) scavenging capacity, ferric ion-reducing antioxidant power (FRAP) and the thiobarbituric acid (TBA) method. The tested plant extracts showed promising antioxidant and free radical scavenging activity, thus justifying their traditional use. Among examined cereals all the applied methods, except TBA method, have shown that buckwheat have the highest antioxidant activity, while among examined legumes results varied depending on the method used.
  • Authors:
    • Korac, M.
    • Meseldzija, M.
    • Konstantinovic, B.
    • Mandic, N.
  • Source: Herbologia
  • Volume: 12
  • Issue: 1
  • Year: 2011
  • Summary: Soil surface contains huge amount of seed of different weed species. By examination of weed seed distribution in the soil, it can be predicted which weeds will occur under different crops and to what extent. Detailed data analysis enables determination of timely soil tillage, as well as herbicide use. In the period 2008-2010, the weed seed bank was studied in different localities on the territory of Vojvodina (Krivaja, Ratkovo, Zmajevo, Bac, and Despotovo). Soil samples were collected from fields under different crops (soybean, sugar beet, maize, clover and sunflower). The sampling was performed diagonally in four replications from several arable depth layers of 0-10, 10-20 and 20-30 cm. Each sample was sieved through the system of cooper sieves of different diameter, according to the method of Conn (1987). After extraction from the samples, weed seeds were determined (Skender et. al., 1998; Kronaveter and Boar, 1994) and abundance of weed seed per m 2 was established for all three studied soil layers. The most abundant weed species in the weed seed bank under all studied crops were: Amaranthus retroflexus, Chenopodium album, Datura stramonium, Polygonum lapathifolium and Solanum nigrum, while less abundant were seeds of: Echinochloa cruss-galli, Euphorbia helioscopia, Sinapis arvensis, Sorghum halepense and Stachys annua. The highest abundance of weed seed was found at locality Zmajevo under sunflower crop in the soil layer of 0-10 cm, in the amount of 8.487 seeds per m 2. At locality Krivaja, under soybean crop, the highest number of seeds was recorded in layers of 10-20 and 20-30, in the amount of 9.252 and 10.609 seeds per m 2, respectively. The results were statistically processed and it was calculated that the highest coefficient of variance, i.e. the maximum deviation between number of seeds of weed species per soil layers was 40.53% at locality Despotovo.
  • Authors:
    • Liu, Y.
    • Ma, L.
    • Li, X.
  • Source: Acta Phytophylacica Sinica
  • Volume: 38
  • Issue: 3
  • Year: 2011
  • Summary: In order to fully understand the regular pattern of the population dynamics of Lithocolletis ringoniella Matsumura in the apple production region of the Loess Plateau, the distribution pattern and the ecological niche index were determined and the clustering analysis was conducted to describe the dynamic change of L. ringoniella population. The results showed that the leaf insect spot caused by L. ringoniella was visible in June; the number of the insect increased in July, with the damage symptom severe in August; and the quantity of the population number was in surge in September and October. The relative abundance of the temporal sequence was in a strong rising trend since August. Population distribution in the crown was uniform in early July and aggregative after that. The spatial distribution among the vertical positions of the tree crown showed significant difference, population number following the order of lower > middle > upper parts, whereas distribution among horizontal directions had no significant difference. The general distribution within the crown appeared in cluster, with individuals attractive to each other. The ecological niche occupation of this pest in vertical and horizontal directions as well as in temporal sequences are 0.179, 0.371 and 0.594, respectively. The resource utilization rate in the lower part of the crown reached 53.73% and almost nothing utilized in the upper part, indicating a more horizontal expansion potential. Viewing from the four directions, the maximum utilization of resources was in the north and east, up to 27.90% and 21.66% respectively. The ecological niche overlap index of L. ringoniella with hawthorn spider mite in vertical and horizontal directions reached 92.65 and 64.95, respectively, in addition to temporal sequence to be 66.36, indicating that hawthorn spider mite is the most intense space-temporal competitor for the limited resources of apple's crown leaves. The dominance degree index of L. ringoniella in the young apple orchard in different intercropping patterns increased over time since August and largest increase happened in the middle of August. The highest dominance degree index was found in soybean-apple intercropping pattern and the lowest index with sweet potato-apple intercropping pattern. The index fluctuated in the orchard with weeds unwell-managed.
  • Authors:
    • Ewusi-Mensah, N.
    • Logah, V.
    • Tetteh, F.
  • Source: Journal of Plant Sciences
  • Volume: 6
  • Issue: 4
  • Year: 2011
  • Summary: A field experiment to evaluate Soil Organic Carbon (SOC) and maize grain yield under different soil amendments and cropping systems was conducted in 2006 and 2007 at the Soil Research Institute, Kwadaso, Kumasi. The experiment was a split plot with three replications. The main plot factor (cropping systems) consisted of continuous maize, maize/soybean intercropping and maize cowpea rotation systems, the sub-plot (amendments) comprised of Poultry Manure (PM) at 4 t ha -1, poultry manure+chemical fertilizer (PM+CF) at 2 t ha -1 (PM)+45-30-30 kg ha -1 (NPK 15-15-15), Chemical Fertilizer (CF) at 90-60-60 kg ha -1 NPK 15-15-15 and a control (no amendment). Soil samples were taken at 21 and 84 days after amendment (DAA). Generally, PM+CF produced the highest range of SOC (1.14-1.37%). The least (0.98-1.28%) was recorded on the control plots. Plots amended with chemical fertilizer alone or in combination with poultry manure out-yielded the control in maize grain yield. Positive correlations between SOC at 84 DAA and maize grain yield were recorded in the major (r=0.70*) and minor (r=0.89**) rainy seasons of 2006 which established crop yield a function of SOC at harvest. Land equivalent ratios of sole maize (maize grown under continuous maize system) and maize intercropped with soybean were
  • Authors:
    • Silva Junior, A.
    • Alves, M.
    • Muraishi, C.
    • Souza, Z.
  • Source: ACTA SCIENTIARUM-AGRONOMY
  • Volume: 33
  • Issue: 3
  • Year: 2011
  • Summary: This study was conducted at the Experimental Station belonging to UNESP Engineering University, Ilha Solteira Campus, based in Selviria, Mato Grosso do Sul State, Brazil, with the aim of evaluating chemical alterations in an Oxisol after being managed for two years with organic and/or chemical fertilization and different tillage systems during the agricultural years of 2004/2005 and 2005/2006. The treatments were: conventional-tillage; chisel tillage and no-tillage; the fertilization treatments were: control (no fertilization); chemical fertilization (300 kg ha -1 from the 20-00-20); organic fertilization (cattle manure - 20 Mg ha -1); organic+1/2 the recommended chemical fertilization for the used crop; 20 and 30 Mg ha -1 of sewage sludge. Soybean was used in the first year and sorghum in the next year, evaluating the soil chemical attributes in four layers. The soil chemical attributes were changed in the first year; the organic fertilization, sewage sludge and organic+chemical fertilization were efficient to change the chemical attributes; the sewage sludge was more efficient in soil P recuperation and, the no-tillage system contributed to soil K increase.
  • Authors:
    • Brye, K.
    • Smith, A.
    • Fortin, C.
    • Nalley, L.
    • Popp, M.
  • Source: Agronomy Journal
  • Volume: 103
  • Issue: 4
  • Year: 2011
  • Summary: In this study, we developed a technique for estimating soil C sequestration from crop production with detailed spatial differences in production practices, tillage effects, and soil textures often overlooked when modeling state-level implications of climate change policies. The model also tracks C equivalent (CE) emissions from fertilizer, fuel, and agricultural chemical use. Using Arkansas as an example, a model that maximizes crop returns to producers in conjunction with C offset payments allowed estimation of probable changes in county-level cropping patterns and income as a result of varying C prices. While income ramifications of a C-offset climate change policy are positive, significant uncertainty about resultant greenhouse gas (GHG) effects are demonstrated. Crops included were corn ( Zea mays L.), cotton ( Gossypium hirsutum L.), grain sorghum [ Sorghum bicolor (L.) Moench], soybean [ Glycine max (L.) Merr.], rice ( Oryza sativa L.) and wheat ( Triticum spp.). As a result of this detailed analysis, two caveats are that (i) policy recommendations hinge on a baseline scenario that would change with changes in input and output price levels, with these interactions not modeled within, and (ii) monitoring costs of a C-offset market could be significant.
  • Authors:
    • Amarante, I.
    • Machado, J.
    • Fontaneli, R.
    • Santos, H.
  • Source: Pesquisa Agropecuaria Gaucha
  • Volume: 17
  • Issue: 1
  • Year: 2011
  • Summary: The effects of soil management systems and crop rotation on sorghum yield characteristics agronomic were evaluated during the period 2003/04 to 2010/11 at EmbrapaTrigo, Passo Fundo, RS, Brazil. Four soil management systems: (1) no tillage, (2) minimum tillage, conventional tillage using a disk plow and a disk harrow, and (4) conventional using a moldboard and a disk harrow; and three crop rotation system I (wheat/soybean), system II (wheat/soybean and common vetch/sorghum), and system III (wheat/soybean, white oats/soybean and common vetch/sorghum) were compared. An experimental design of blocks at random, with split-plots and three replications, was used. The main plot was formed by the soil management systems, while the split-plot constituted of the crop rotation systems. Minimum tillage and no-tillage presented higher yield of sorghum, while conventional tillage using a moldboard plow remained in intermediate position and tillage using disk plow the lowest yield of sorghum. The yield of sorghum grown after common vetch in system II was higher than yield obtained for sorghum after common vetch in system I. No significant differences were observed in sorghum characteristics agronomic as a result of soil management and crop rotation systems.