• Authors:
    • Kaul, H. -P
    • Loiskandl, W.
    • Himmelbauer, M.
    • Bodner, G.
  • Source: Agronomy for Sustainable Development
  • Volume: 30
  • Issue: 2
  • Year: 2010
  • Summary: Cover crops are plants that are integrated in the crop rotation between two cash crops. The main objectives of cover cropping are organic matter input, mitigation of nitrate leaching and reduction of soil erosion. These benefits will only be achieved efficiently if the selected cover crop species are adapted to local environmental conditions and appropriate for the defined agro-ecological target. Therefore, a main limitation in cover cropping is the lack of a comprehensive species description. An improved cover crop characterization could be achieved with quantitative parameters derived from growth functions. Here, we show the use of this approach to assess plant traits relevant for erosion control by cover cropping. An experiment with four cover crop species (phacelia, vetch, rye and mustard) was performed over two years at a semi-arid site in Eastern Austria. Canopy cover was measured four times over the vegetation period. Root length density measurements were made to 40 cm soil depth before winter. Canopy dynamics were characterized by parameters from the asymptotic Gompertz function and from an extended logistic model that includes a parameter for decay after maximum coverage. Our results show that vetch had the lowest early vigor after dry conditions at sowing, with +45% longer time to attain maximum growth rate (parameter t(max)) than the other species. Drought during the later autumn growing period led to the highest reduction in maximum canopy cover (parameter y(max)) for phacelia (-41%). The rooting pattern was assessed by parameters from the exponential distribution function of Gerwitz and Page. The most intense rooting near the soil surface (parameter L(0)) was found for phacelia (9.7 cm cm(-3)). Vetch had the lowest L(0) (4.6 cm cm(-3)) but highest root allocation to deeper soil layers. Mustard combined high average values in y(max) (76%) and L(0) (6.3 cm cm(-3)) with a stable growth over both years. The potential strengths of phacelia and vetch were more dependent on the particular year. Rye showed a stably high L(0) (8.6 cm cm(-3)), but had only a low average value of y(max) (55.1%). The quantitative parameter sets we derived for plant traits required for erosion control improved cover crop comparison and analysis of their local adaptation. Based on this extended species description our approach allows a better evaluation of cover crops and can be used for the optimization of management and decision support.
  • Authors:
    • Domuta, C.
    • Sandor, M.
    • Bara, L.
    • Bara, C.
    • Bara, V.
    • Domuta, C.
    • Borza, I. M.
    • Brejea, R.
    • Vuscan, A.
  • Source: Analele Universităţii din Oradea, Fascicula: Protecţia Mediului
  • Volume: 15
  • Year: 2010
  • Summary: The paper based on the researche carried out in the Agricultural Research and Development Station Oradea in the long term trial placed in 1990 on a preluvosoil. Two factors were studied: crop rotation (maize-monocrop; maize-wheat; maize-soybean-wheat) and water regime (unirrigated and irrigated). In comparison with unirrigated and irrigated monocrop, in the maize-wheat crop and especially in the maize-soybean-wheat crop rotation very significant yield gains were obtained all the three years. The irrigation determined the yield gains very significant statistically every year and in every crop rotation. The smallest protein content and protein production were registered in the variant with maize monocrop and the biggest in the variant with wheat-maize-soybean crop. The irrigation determined the increase of the protein content.
  • Authors:
    • Martz, L. W.
    • Pomeroy,J. W.
    • Armstrong, R. W.
  • Source: Canadian Water Resources Journal
  • Volume: 35
  • Issue: 2
  • Year: 2010
  • Summary: Physically-based atmospheric models of evapotranspiration (ET) that consider the Penman combination energy balance and aerodynamic approach have achieved acceptance as useful tools for obtaining estimates of actual ET from land surfaces. These models have been made applicable to the case of non-saturated conditions through either surface resistance formulations (e.g., Penman-Monteith) or by application of the complementary evaporation theory of feedback between the atmosphere and surface moisture states (e.g., Granger-Gray). Their application becomes complicated under conditions of drought, when extremely low soil moisture availability severely restricts ET from the soil and plants. Under such severe conditions, consideration for the surface water balance and interactions with the balance of available energy and aerodynamic principles are Important for accurately estimating actual ET A modelling application is demonstrated using the Cold Regions Hydrological Model (CRHM) platform to examine the estimation of ET under drought conditions. CRHM allows users to assemble hydrological models by linking a suite of modular physically-based algorithms that describe the individual processes. In this case, the models assembled consider infiltration, evaporation, and sod moisture accounting and are applied to a mixed prairie located at Lethbridge, Alberta, Canada under drought conditions during the growing period in 2000 and 2001. Near surface meteorological and ecological observations used as model input and for evaluating model performance were obtained through the Ameriflux network and the Agriculture and Agri-Food Canada (AFC) Lethbridge Research Centre Results show that consideration for the effective rooting zone depth of the mixed-prairie at the site is important for estimating actual ET using the Penman-Montieth and Granger-Gray models during severe moisture stress. Relative differences in ET estimates provided by the models are discussed in the context of their contrasting theoretical approaches.
  • Authors:
    • Paltridge, N.
    • Tao, J.
    • Unkovich, M.
    • Gason, A.
    • Grover, S.
    • Wilkins, J.
    • Coventry, D.
    • Tashi, N.
    • Bonamano, A.
  • Source: Crop & Pasture Science
  • Volume: 60
  • Issue: 7
  • Year: 2009
  • Summary: In the south of the Tibet Autonomous Region of China there is a network of valleys where intensive agriculture is practiced. Although considered highly productive by Tibetans, farm incomes in the region are low, leading to a range of government initiatives to boost grain and fodder production. However, there is limited information available on current farming practices, yields, and likely yield constraints. The present paper uses available data and farmer interviews to describe the agro-climate and current systems of crop and livestock production, and considers possible strategies to boost production. Although winters in Tibet are cold and dry, summer and autumn provide ideal conditions for crop growth. Cropping systems are characterised by heavy tillage, frequent irrigation, high seeding rates and fertiliser applications, some use of herbicides, and little stubble retention or mechanisation. Spring barley and winter wheat are the predominant crops, followed by rapeseed, winter barley, and minor fodder and vegetable crops. Average yields for the main grain crops are around 4.0 t/ha for spring barley and 4.5 t/ha for winter wheat, significantly lower than should be possible in the environment. Farmers typically keep five or six cattle tethered near the household. Cattle are fed diets based on crop residues but are generally malnourished and rarely produce beyond the needs of the family. It is suggested that research and extension in the areas of crop nutrition, weed control, irrigation, seeding technology, and crop varieties should enable significant increases in grain yield. Increases in cattle production will require increases in the supply of good quality fodder. Cereal/fodder intercrops or double crops sown using no-till seed drills might enable the production of useful amounts of fodder in many areas without jeopardising food grain supply, and allow more crop residues to be retained in fields for improved soil health.
  • Authors:
    • Schindler, U.
    • Muller, L.
  • Source: Proceedings of the 10th International Agricultural Engineering Conference
  • Year: 2009
  • Summary: Land management practice is a decisive factor for the quantities of seepage flow and solute leaching, which constitute two fundamental aspects of land use characterised by potentially conflictive ecologic implications. Efficient water use and intelligent water management are essential for Northeast Germany as a sub-humid region marked by an annual water balance deficit between 80 and 250 mm. Throughout that region, measures are in demand to support groundwater recharge. To meet this claim, knowledge is required about suitable land management systems providing drainage flow sustainable in quantity and quality. Long-term soil hydrological measurements were used to quantify deep drainage and nitrate leaching insitu under undisturbed soil conditions. Deep drainage rates and nitrate losses from arable land managed under various farming regimes (integrated, integrated with irrigation, ecologic and low input) and tillage systems (plough and no till) were quantified in the Pleistocene region of Northeast Germany from 1994 to 2007. Soil water content and tension measurements down to 3 m depth and soil water sampling were used to determine deep drainage dynamics and loss of nitrogen by leaching. As dependent on the management system, the nitrate concentration varied between 40 and 150 mg l -1. In connection with annual deep drainage rates between 100 mm and 200 mm during the study period, the annual nitrogen loss varied between 14 and 41 kg ha -1. Differences in nitrogen loss observed between the farming systems were low, but yields increased and nitrogen losses decreased as a result of irrigation throughout the variants. No-till treatment resulted in reduced nitrate leaching (18 kg ha -1) as compared with the tillage system with plough and tooth cultivator (27 kg ha -1). The suitability of long-term soil hydrological in-situ measurements for quantifying arable management effects on ecological processes - deep drainage dynamics and solute leaching - was confirmed. The trend of decreasing deep drainage was low and not significant. However, due to no significance and quite short investigation period it is not allowed to suggest on climate change effects.
  • Authors:
    • Haber, S. M.
    • Fetch, T. G.,Jr.
    • Chong, J.
    • Ames, N.
    • Duguid, S. D.
    • Brown, P. D.
    • Fetch, J. W. M.
    • Menzies, J. G.
    • Stadnyk, K. D.
  • Source: Canadian Journal of Plant Science
  • Volume: 89
  • Issue: 1
  • Year: 2009
  • Summary: Jordan is a high-yielding, white-hulled spring oat ( Avena sativa L.) cultivar postulated to carry the crown rust resistance combination Pc38, Pc39, and Pc68, which was effective against the prevalent pathotypes of crown rust races on the Canadian prairies at the time of its release. It has very good resistance to loose and covered smut, moderately good resistance to most of the prairie stem rust races (likely due to the presence of Pg2 and Pg13) and moderate tolerance to barley yellow dwarf virus (BYDV). Jordan has high kernel weight, high percent plump kernels, and low percent thin kernels. Jordan exhibits high yielding capacity in the oat growing areas of western Canada. Jordan was supported for registration at the Prairie Grain Development Committee Meeting in February 2005.
  • Authors:
    • Menzies, J. G.
    • Fetch, T. G.
    • Clayton, G. W.
    • Chong, J.
    • Kibite, S.
    • Fetch, J. W. M.
    • Turkington, T. K.
  • Source: Canadian Journal of Plant Science
  • Volume: 89
  • Issue: 4
  • Year: 2009
  • Summary: Lee Williams is a high-yielding hulless oat ( Avena sativa L.) with good disease resistance and good straw strength. It is well adapted to all of the oat producing regions of western Canada. It carries genetic resistance to several races of crown rust (caused by Puccinia coronata Corda f. sp. avenea Eriks.) and stem rust (caused by P. graminis f. sp. avenae Pers.), loose [ Ustilago avenae (Pers.) Rostr.], and covered smut ( U. kolleri Wille), and moderate resistance to barley yellow dwarf virus (BYDV). Lee Williams has protein and oil levels and a high groat to hull ratio that make it well-suited for livestock feed. Hulless oat may retain a low percentage of hulls after threshing so a high groat to hull ratio is desirable. Lee Williams was supported for registration at the Prairie Regional Recommending Committee for Grains meeting in February 2002.
  • Authors:
    • Kosterna, E.
    • Zaniewicz-Bajkowska, A.
    • Jabonska-Ceglarek, R.
    • Franczuk, J.
    • Rosa, R.
  • Source: Vegetable Crops Research Bulletin
  • Volume: 70
  • Year: 2009
  • Summary: The effect of three methods of soil mulching: autumn or spring ploughing and leaving mulch as a cover crop on the soil surface without incorporation till the end of cabbage growth on the contents of selected nutrients in red cabbage and onion was investigated. The following plants were used as intercropped mulches: phacelia, vetch, Serradella and oat. Mulching effects were compared to a non-mulched control as well as a farmyard manure application at the rate of 40 t.ha -1. Nutrient content in both vegetable species depended on weather conditions and varied in study years. Accumulation of dry matter in cabbage was favoured by phacelia and oat mulches, irrespective of the date of ploughing. Non-incorporated oat and autumn-incorporated phacelia increased dry matter content in onion. An increase in the protein content in cabbage was observed when following Serradella and vetch mulches. The protein content in onion cultivated in the second year following mulching did not change significantly as a result of the influence of examined factors. Among an the mulches taken into study, Serradella and oat increased the content of vitamin C in cabbage. Similarly, autumn- or spring-incorporated oat mulch and non-incorporated Serradella mulch increased the content of vitamin C in onion.
  • Authors:
    • Hirata, T.
    • Hoshino, Y.
    • Hane, S.
    • Hajime, A.
  • Source: Horticulture Environment and Biotechnology
  • Volume: 50
  • Issue: 4
  • Year: 2009
  • Summary: More than 70% of fresh tomato is produced in plastic high tunnel or greenhouse and much fertilizer and agricultural chemicals have been applied for tomato production. Cover crop is one of the important tools for sustainable agro-production because of improving soil properties. Effect of cover cropping on soil properties and tomato production in plastic high tunnel was examined in Sapporo, Japan, snow cover region. Plastic high tunnel was set before snow-melting, late in March, 2007. Two cover crops, legume (hairy vetch; Vicia villosa R.) and non legume (wild oat; Avena sterigosa L.), were planted each alone or mix-planted in the plot (0.8 m in width and 3.5 m in length) early in April. Seeding density in mono-culture was 5 kg/10a in hairy vetch and 10 kg/10a in wild oat. For bi-culture, density was 3.5 kg/10a in hairy vetch and 5 kg/10a in wild oat. Above ground biomass (dry weight) was shown 445 kg/10a in hairy vetch and 982 kg/10a in wild oat late in May. However, in mix-culture, it was 190 kg/10a in hairy vetch and 602 kg/10a in wild oat. Cover crops were killed for residue mulch just before tomato planting. Seedlings of tomato 'Momotaro' were planted in the plots covered with cover crop residue and 12 kg/10a N fertilizer application (12 kg N/10a) and bare plot with 12 kg/10a or 24 kg/10a N fertilizer (24 kg N/10a) application. Nitrate concentration of the petiole sap in the leaf just below the first fruit cluster was higher in the tomatoes grown in bare plot with 24 kg N/10a and in hairy vetch mulch with 12 kg N/10a at 40 days after transplanting. Large yield was shown in bare plot with 24 kg N/10a (7.9 t/10a) and in hairy vetch plot with 12 kg N/10a (7.8 t/10a). The yield in bare plot with 12 kg N/10a and Mix plot with 12 kg N/10a was 6.9 t/10a. The yield in wild oat plot with 12 kg N/10a was the smallest (6.1 t/10a). Soil carbon in the plots with cover crop mulch became higher than that of bare plots after tomato production. It will be possible to obtain current yield and to increase soil carbon in cover cropping with reduction of N fertilizer. This technique will lead the organically grown system in plastic high tunnel production.
  • Authors:
    • Mann, D.
    • Ranjan, R.
    • Kahimba, F.
  • Source: Applied Engineering in Agriculture
  • Volume: 25
  • Issue: 6
  • Year: 2009
  • Summary: Soil freezing and thawing processes and soil moisture redistribution play a critical role in the hydrology and microclimate of seasonally frozen agricultural soils. Accurate simulations of the depth and timing of frost and the redistribution of soil water are important for planning farm operations and choosing rotational crops. The Simultaneous Heat and Water (SHAW) model was used to predict soil temperature, frost depth, and soil moisture in agricultural soils near Carman, Manitoba. The model simulations were compared with three years of field data collected from summer 2005 to the summer 2007 in four cropping system treatments (oats with berseem clover cover crop, oats alone, canola, and fallow). The simulated soil temperatures compared well with the measured data in all the seasons (R 2=0.96-0.99). The soil moisture simulations were better during the summer (RMSE=9.1-12.0% of the mean) compared to the winter seasons (RMSE=17.5-19.7% of the mean). During the winter, SHAW over-predicted by 0.02 to 0.10 m 3 m -3 the amount of total soil moisture below the freeze front and under-predicted by 0.02 to 0.05 m 3 m -3 the soil moisture in the upper frozen layers. The model was revised to account for the reduction in effective pore space resulting from frozen water to improve the winter soil moisture predictions. After this revision, the model performed well during the winter (RMSE=14.4% vs. 17.5%; R 2=0.74 vs. 0.67 in vegetated treatments, and RMSE=12.9% vs. 19.7%; R 2=0.73 vs. 0.52 in fallow treatments). The modified SHAW model is an enhanced tool for predicting the soil moisture status as a function of depth during spring thawing, and for assessing the availability of soil moisture at the beginning of the subsequent growing season.