• Authors:
    • Provance-Bowley, M.
    • Wyenandt, C. A.
    • Heckman, J. R.
  • Source: Journal of Sustainable Agriculture
  • Volume: 35
  • Issue: 6
  • Year: 2011
  • Summary: When municipal shade tree leaves (MCST-leaf) are used as mulch the residues impact soil fertility for crops in the rotation. Pumpkin (Cucurbita pepo L.), grown near Pittstown, New Jersey, using leaf mulch, was followed in the next year by sweet corn (Zea mays L.) and by a fall-seeded rye (Secale cereale L.) cover crop. A 15 cm layer of MCST-leaf mulch adds an estimated 448 kg ha(-1) of N organically bound within 45 Mg ha(-1) of leaf dry matter. Because of the high C/N ratio, little of this N becomes available in the first growing season as was apparent from the N immobilization and N deficiency temporarily observed when the land was initially cropped to pumpkin. Sweet corn ear size was increased on amended soil compared to unamended soil. Crop responses with both sweet corn and rye indicated that significant amounts of nitrogen became plant available from leaf mulch decomposition. Leaf mulch improves soil fertility for several years after incorporation but in ways not apparent through soil nitrate testing. Besides enhanced N nutrition, sweet corn ear size on MCST-leaf amended soil may be related to other improvements in soil quality such as increased water holding capacity.
  • Authors:
    • Olson, B. L.
    • Schlegel, A. J.
    • Holman, J. D.
    • Maxwell, S. R.
  • Source: Crop Management
  • Issue: June
  • Year: 2011
  • Summary: A common crop rotation in the west-central Great Plains is no-till winter wheat-corn-fallow. Because most of the corn produced is herbicide-tolerant, volunteer corn in fallow is not controlled with glyphosate. This study evaluated the impact of volunteer corn on soil moisture storage in fallow and the succeeding winter wheat crop across three locations in western Kansas from 2008 to 2010. Volunteer corn reduced available soil water at wheat planting in 8 out of 9 site years. On average, available soil water was reduced by 1 inch for each 2,500 volunteer corn plants per acre. Volunteer corn water use reduced wheat tillers in half of the site years. Similarly, volunteer corn reduced wheat yields in half of the site years, and yields fell 1 bu/acre for every 500 volunteer corn plants per acre. When wheat yields were above 70 bu/acre or below 35 bu/acre, other factors affected wheat yield more than the preceding volunteer corn population or available soil water at wheat planting.
  • Authors:
    • Walter-Shea, E. A.
    • Singh, R. K.
    • Irmak, A.
    • Verma, S. B.
    • Suyker, A. E.
  • Source: Transactions of the American Society of Agricultural and Biological Engineers and Papers in Natural Resources. Paper 334.
  • Volume: 54
  • Issue: 1
  • Year: 2011
  • Summary: We evaluated the performance of four models for estimating soil heat flux density (G) in maize (Zea mays L.) and soybean (Glycine max L.) fields under different irrigation methods (center-pivot irrigated fields at Mead, Nebraska, and subsurface drip irrigated field at Clay Center, Nebraska) and rainfed conditions at Mead. The model estimates were compared against measurements made during growing seasons of 2003, 2004, and 2005 at Mead and during 2005, 2006, and 2007 at Clay Center. We observed a strong relationship between the G and net radiation (R n) ratio (G/R n) and the normalized difference vegetation index (NDVI). When a significant portion of the ground was bare soil, G/R n ranged from 0.15 to 0.30 and decreased with increasing NDVI. In contrast to the NDVI progression, the G/R n ratio decreased with crop growth and development. The G/R n ratio for subsurface drip irrigated crops was smaller than for the center-pivot irrigated crops. The seasonal average G was 13.1%, 15.2%, 10.9%, and 12.8% of R n for irrigated maize, rainfed maize, irrigated soybean, and rainfed soybean, respectively. Statistical analyses of the performance of the four models showed a wide range of variation in G estimation. The root mean square error (RMSE) of predictions ranged from 15 to 81.3 W m -2. Based on the wide range of RMSE, it is recommended that local calibration of the models should be carried out for remote estimation of soil heat flux.
  • Authors:
    • Esker, P. D.
    • Jirak-Peterson, J. C.
  • Source: Plant Disease
  • Volume: 95
  • Issue: 5
  • Year: 2011
  • Summary: Corn anthracnose (Colletotrichum graminicola) is an important disease of field coni (Zea mays). Two phases, leaf blight and stalk rot, can reduce yield through either premature leaf senescence or reduced grain harvest due to stalk lodging. Corn residue is an important source of primary inoculum and is increased through cultural practices such as no-tillage and continuous corn cropping, which are common practices in Wisconsin. Field studies conducted at the Arlington Agricultural Research Station (ARS) and the West Madison ARS showed that the incidence and severity of anthracnose leaf blight were higher in continuous-corn crop rotations than in soybean corn rotations (91% higher incidence, 24 to 78% higher severity). Anthracnose stalk rot was marginally affected by tillage in 2008 (P = 0.09), with higher incidence in chisel-plowed treatments. There was a positive association between spring residue cover and anthracnose leaf blight but no association was found between residue and stalk rot. No association was found between anthracnose leaf blight and stalk rot. There was a negative association between anthracnose leaf blight and yield but not between anthracnose stalk rot and yield. Managing residue levels through crop rotation would help to reduce anthracnose leaf blight but further work is needed to elucidate factors that lead to stalk lodging prior to harvest.
  • Authors:
    • Verma, S. B.
    • Vanegas, D. X.
    • Xiao, X. M.
    • Kalfas, J. L.
    • Suyker, A. E.
  • Source: Agricultural and Forest Meteorology
  • Volume: 151
  • Issue: 12
  • Year: 2011
  • Summary: Information on gross primary production (GPP) of maize croplands is needed for assessing and monitoring maize crop conditions and the carbon cycle. A number of studies have used the eddy covariance technique to measure net ecosystem exchange (NEE) of CO 2 between maize cropland fields and the atmosphere and partitioned NEE data to estimate seasonal dynamics and interannual variation of GPP in maize fields having various crop rotation systems and different water management practices. How to scale up in situ observations from flux tower sites to regional and global scales is a challenging task. In this study, the Vegetation Photosynthesis Model (VPM) and satellite images from the Moderate Resolution Imaging Spectroradiometer (MODIS) are used to estimate seasonal dynamics and interannual variation of GPP during 2001-2005 at five maize cropland sites located in Nebraska and Minnesota of the U.S.A. These sites have different crop rotation systems (continuously maize vs. maize and soybean rotated annually) and different water management practices (irrigation vs. rain-fed). The VPM is based on the concept of light absorption by chlorophyll and is driven by the Enhanced Vegetation Index (EVI) and the Land Surface Water Index (LSWI), photosynthetically active radiation (PAR), and air temperature. The seasonal dynamics of GPP predicted by the VPM agreed well with GPP estimates from eddy covariance flux tower data over the period of 2001-2005. These simulation results clearly demonstrate the potential of the VPM to scale-up GPP estimation of maize cropland, which is relevant to food, biofuel, and feedstock production, as well as food and energy security.
  • Authors:
    • Sarauskis, E.
    • Karayel, D.
  • Source: Žemės Ūkio Inžinerija, Mokslo Darbai
  • Volume: 43
  • Issue: 3
  • Year: 2011
  • Summary: Seed placement uniformity and failure to establish a uniform plant stand are critical problems associated with no-tillage production of maize ( Zea mays L.) following wheat ( Triticum aestivum). The objective of this research was to evaluate the effect of different downforces (680, 880, 1150 and 1400 N) on performance of disc furrow openers and determine the optimum downforce for modified precision seeder equipped with single or double disc-type openers. The study was conducted in two different field conditions (field I and field II). The soil of field I and II were clay-loam and loamy, respectively. Seed spacing uniformity, sowing depth uniformity, mean emergence time and percentage of emergence were determined. Sowing depth and seed spacing uniformity, mean emergence time and percentage of emergence of both furrow openers were increased as a result of increasing downforce for both fields. The downforce of modified conventional precision seeder should be greater than 880 N for more precise no-till sowing using with single and double disc furrow openers for clay-loam and loamy soils.
  • Authors:
    • Zhang, F. S.
    • Sun, J. H.
    • Li, L.
  • Source: Soil Science and Plant Nutrition
  • Volume: 57
  • Issue: 1
  • Year: 2011
  • Summary: Intercropping two species at different growth stages is common in temperate and tropical areas. An apparent recovery of growth is observed in late-maturing species after early-maturing species have been harvested, but the mechanism remained unclear. This study tested the hypothesis that the roots of late-maturing species occupy greater below-ground space at later growth stages. The monolith method was employed to investigate the spatial and temporal distribution of maize grown alone (no interspecific interactions), maize intercropped with wheat (asymmetric interspecific facilitation before wheat harvesting), and maize intercropped with faba bean (symmetric interspecific facilitation) on August 8, September 2 and September 30, after harvesting of wheat (July 15) or faba bean (August 2). The results show that maize intercropped with wheat occupied more below-ground space at late growth stages than at early growth stages when the two crops grew at the same time, thus supporting our hypothesis. Furthermore, we also found that interspecific interactions during the co-growth stage of the two species led to a longer root life span in both maize intercropped with wheat and faba bean compared to the maize grown alone. The findings may partly explain the recovery of late-maturing species found in intercropping systems between two crop species with different growth stages and the complementary effect on the relationship between plant biodiversity and productivity.
  • Authors:
    • Hernandez, R. M.
    • Bravo, C.
    • Rivero, C.
    • Lozano P.,Z.
  • Source: REVISTA DE LA FACULTAD DE AGRONOMIA DE LA UNIVERSIDAD DEL ZULIA
  • Volume: 28
  • Issue: 1
  • Year: 2011
  • Summary: Some researchers suggest the use of different SOM organic matter (SOM) fractions or compartiments like indicators of the agricultural systems sustainability. In order to evaluate the amount, composition and distribution in the profile of different SOM fractions from the soil on conservation agriculture systems, evaluations in an Ustoxic Quartzipsament soil located at Venezuelan savannahs, were carried out. Three cover crop treatments were evaluated, as improved land fallows for the establishing of maize no-tillage system and grazing with ovine cattle: Brachiaria dictyoneura (BD), Centrosema macrocarpum (CM), and spontaneous vegetation (SV), and its comparison with the natural savannah ecosystem (NS). Samples to three depths (0-5, 5-15 and 15-30 cm), and were taken at three times: initial, 286 days after the establishment (dae), and 1463 dae. At all depths and to 1463 dae were evaluated: total organic carbon (TOC), hidrosoluble carbon (HSC), and particulate organic matter carbon (POMC). At all times and in the the 0 to 5 cm layer physical and chemical fractions of the SOM, were evaluated. The results show statistical differences between cover crops types in some SOM fractions, mainly in the light fractions (HSC, and fulvic acid carbon), with the greater values in BD and the minors in SV. The cover crops introduction produced the diminution in some fractions; but after three continuous cycles under the proposed management, these fractions reached similar values or superior to those initials. The humification indexes, and the relations between the different fractions and the TOC, were the most sensible indicators.
  • Authors:
    • Pecchioni, N.
    • Perata, P.
    • Milc, J.
    • Meriggi, P.
    • Arru, L.
    • Caffagni, A.
  • Source: Communications in Soil Science and Plant Analysis
  • Volume: 42
  • Issue: 6
  • Year: 2011
  • Summary: Iodine is an essential microelement for human health, and the recommended daily allowance (RDA) of such element should range from 40 to 200 g day -1. Because of the low iodine contents in vegetables, cereals, and many other foods, iodine deficiency disorder (IDD) is one of the most widespread nutrient-deficiency diseases in the world. Therefore, investigations of I uptake in plants with the aim of fortifying them can help reach the important health and social objective of IDD elimination. This study was conducted to determine the effects of the absorption of iodine from two different chemical forms - potassium iodide (I -) and potassium iodate (IO -3) - in a wide range of wild and cultivated plant species. Pot plants were irrigated with different concentrations of I - or IO -3, namely 0.05% and 0.1% (w/v) I - and 0.05%, 0.1%, 0.2%, and 0.5% (w/v) IO -3. Inhibiting effects on plant growth were observed after adding these amounts of iodine to the irrigation water. Plants were able to tolerate high levels of iodine as IO -3 better than I - in the root environment. Among cultivated species, barley ( Hordeum vulgare L.) showed the lowest biomass reductions due to iodine toxicity and maize ( Zea mays L.) together with tobacco ( Nicotiana tabacum L.) showed the greatest. After the screening, cultivated tomato and potato were shown to be good targets for a fortification-rate study among the species screened. When fed with 0.05% iodine salts, potato ( Solanum tuberosum L.) tubers and tomato ( Solanum lycopersicum L.) fruits absorbed iodine up to 272 and 527 g/100 g fresh weight (FW) from IO -3 and 1,875 and 3,900 g/100 g FW from I -. These uptake levels were well more than the RDA of 150 g day -1 for adults. Moreover, the agronomic efficiency of iodine accumulation of potato tubers and tomato fruits was calculated. Both plant organs showed greater accumulation efficiency for given units of iodine from iodide than from iodate. This accumulation efficiency decreased in both potato tubers and tomato fruits at iodine concentrations greater than 0.05% for iodide and at respectively 0.2% and 0.1% for iodate. On the basis of the uptake curve, it was finally possible to calculate the doses of supply in the irrigation water of iodine as iodate (0.028% for potato and 0.014% for tomato) as well as of iodide (0.004% for potato and 0.002% for tomato) to reach the 150 g day -1 RDA for adults in 100 g of such vegetables, to efficiently control IDD, although these results still need to be validated.
  • Authors:
    • Mapurazi, S.
    • Mapfaire, L.
    • Masona, C.
    • Makanda, R.
  • Source: Journal of Sustainable Development
  • Volume: 4
  • Issue: 6
  • Year: 2011
  • Summary: A study was carried out in March 2010 at Firle Sewage Works in Harare, Zimbabwe to determine the effects of long term wastewater irrigation on the concentrations of heavy metals (Zn, Cu, Mn, Cd, Pb, Ni, Fe and Cr) in soil, and their subsequent accumulation in maize plants. The study revealed that long term wastewater use for irrigation results in heavy metal accumulation in soils and bioaccumulation in plants beyond maximum permissible limits (MPL) for both humans and livestock consumption. Lead had highest transfer factor and iron had the least transfer factor. The soil pH was found to be less acidic (pH=5.6) in soils exposed to waste water than in soils where no wastewater had been applied (pH=5). As a recommendation there is need for phytoextraction of heavy metals by intercropping maize plants with local agro forestry shrubs to reduce amount of heavy metals in the soil.