• Authors:
    • Pieterse, P. J.
    • Zhou, M.
    • Tagwira, F.
    • Shoko, M. D.
  • Source: World Journal of Agricultural Sciences
  • Volume: 5
  • Issue: 1
  • Year: 2009
  • Summary: The use of non-destructive devices like Delta-T-Leaf-Area-Meter and Canegro Models can help farmers to manage their cane crops and have an understanding of the importance of measurement of physiological parameters so as to maximize cane and sugar yields. This study was conducted on sandy clay loams of the lithosol group under the Zimbabwe soil classification system at The Zimbabwe Sugar Association Experiment Station (ZSAES). The main aim of this study was to establish the most economic rate of N fertilizer when vegetable and grain soybean are used as fallow crops in sugarcane production systems. The following cane parameters were measured: LAI, biomass, N in leaves and sugarcane and sugar yields. Sugarcane variety N14 was used in the experiment. Post vegetable soybean cane topdressed with 80 kg Nha 1 had the greatest LAI at 150 DAE. The highest biomass was realized on sugarcane topdressed with 80 and 120 kg Nha 1. At final tiller stability post vegetable cane top dresses with 80 kg Nha 1 had the most tiller population. N in leaves and cane and sugar yields were also highest on post vegetable soybean cane and topdressed with kg Nha 1. Tiller density or population and biomass production are important crop variables that are used to estimate the final cane stalk population and sucrose yields. So farmers can top-dress their cane with 80 kg Nha 1 when vegetable soybean are used as fallow crops. This will help them save about 40 kg Nha 1.
  • Authors:
    • Singh, R. K.
    • Irmak, A.
  • Source: Journal of Irrigation and Drainage Engineering
  • Volume: 135
  • Issue: 5
  • Year: 2009
  • Summary: Crop coefficient (Kc) based estimation of crop evapotranspiration (ETc) is one of the most commonly used methods for irrigation water management. The standardized FAO56 Penman-Monteith approach for estimating ETc from reference evapotranspiration and tabulated generalized Kc values has been widely adopted worldwide to estimate ETc . In this study, we presented a modified approach toward estimating Kc values from remotely sensed data. The surface energy balance algorithm for land model was used for estimating the spatial distribution of ETc for major agronomic crops during the 2005 growing season in southcentral Nebraska. The alfalfa-based reference evapotranspiration (ETr) was calculated using data from multiple automatic weather stations with geostatistical analysis. The Kc values were estimated based on ET c and ETr (i.e., Kc = ETc / ETr ). A land use map was used for sampling and profiling the Kc values from the satellite overpass for the major crops grown in southcentral Nebraska. Finally, a regression model was developed to establish the relationship between the normalized difference vegetation index (NDVI) and the ETr -based crop coefficients ( Kcr ) for corn, soybeans, sorghum, and alfalfa. We found that the coefficients of variation (CV) for NDVI, as well as for Kcr of crops were lower during the midseason as compared to the early and late growing seasons. High CV values during the early growing season can be attributed to differences in planting dates between the fields, whereas high CVs during the late season can be attributed to differences in maturity dates of the crops, variety, and management practices. There was a good relationship between Kcr and NDVI for all the crops except alfalfa. Validation of the developed model for irrigated corn showed very promising results. There was a good correlation between the NDVI-estimated Kcr and the Bowen ratio energy balance system based Kcr with a R2 of 0.74 and a low root mean square difference of 0.21. This approach can be a very useful tool for a large (watershed or regional) scale estimation of evapotranspiration using the crop coefficient and reference evapotranspiration approach.
  • Authors:
    • Suyker, A. E.
    • Verma, S. B.
  • Source: Agricultural and Forest Meteorology
  • Volume: 149
  • Issue: 3/4
  • Year: 2009
  • Summary: We have been making year-round measurements of mass and energy exchange in three cropping systems: (a) irrigated continuous maize, (b) irrigated maize-soybean rotation, and (c) rainfed maize-soybean rotation in eastern Nebraska since 2001. In this paper, we present results on evapotranspiration (ET) of these crops for the first 5 years of our study. Growing season ET in the irrigated and rainfed maize averaged 548 and 482 mm, respectively. In irrigated and rainfed soybean, the average growing season ET was 452 and 431 mm, respectively. On average, the maize ET was higher than the soybean ET by 18% for irrigated crops and by 11% for rainfed crops. The mid-season crop coefficient Kc (=ET/ET 0 and ET 0 is the reference ET) for irrigated maize was 1.030.07. For rainfed maize, significant dry-down conditions prevailed and mid-season Kc was 0.840.20. For irrigated soybean, the mid-season Kc was 0.980.02. The mid-season dry down in rainfed soybean years was not severe and the Kc (0.900.13) was only slightly lower than the values for the irrigated fields. Non-growing season evaporation ranged from 100 to 172 mm and contributed about 16-28% of the annual ET in irrigated/rainfed maize and 24-26% in irrigated/rainfed soybean. The amount of surface mulch biomass explained 71% of the variability in non-growing season evaporation totals. Water use efficiency (or biomass transpiration efficiency), defined as the ratio of total plant biomass ( YDM) to growing season transpiration ( T) was 5.200.34 and 5.220.36 g kg -1, respectively for irrigated and rainfed maize crops. Similarly, the biomass transpiration efficiency for irrigated and rainfed soybean crops was 3.210.35 and 2.960.30 g kg -1. Thus, the respective biomass transpiration efficiency of these crops was nearly constant regardless of rainfall and irrigation.
  • Authors:
    • Todorova, R.
  • Source: Rasteniev'dni Nauki
  • Volume: 46
  • Issue: 4
  • Year: 2009
  • Summary: As a result of long research work on genetic improvement of soybean, new varieties have been developed and rich germplasm has been obtained. Classic breeding methods of hybridization and experimental mutagenesis were used. Our studies were directed to obtaining of varieties with high productive potential and resistance to biotic and abiotic stress, as well as to increase of crude protein and crude fat content. The candidate variety Rosa was presented for testing in the system of EAVTFISC (Executive Agency for Variety Testing, Field Inspection and Seed Control). In our competition variety trials it possessed high productive potential under irrigated and nonirrigated conditions and showed resistance to the diseases of bacteriosis and mildew.
  • Authors:
    • Chen, P.
    • Gbur, E. E.
    • Popp, J. H.
    • Brye, K. R.
    • Verkler, T. L.
    • Amuri, N.
  • Source: Journal of Sustainable Agriculture
  • Volume: 33
  • Issue: 7
  • Year: 2009
  • Summary: Soil, water, and air quality can be positively impacted by alternative crop residue management practices that return residue to the soil. Double-crop production systems, particularly those with a grass included in the rotation, rely on successful residue management practices. Soil quality and overall soil tilth are often low in regions with a long history of intensely cultivated, row-crop production, such as in the Mississippi River Delta region of the mid-South. Therefore, the objective of this study was to evaluate the effects of alternative residue (i.e., tillage, residue burning, and residue level) and water management practices on soil properties, soybean [ Glycine max (L.) Merr.] production, and net economic returns, over two consecutive rotations in a wheat ( Triticum aestivum L.) - soybean double-crop system in the Mississippi River Δ region of eastern Arkansas. Initiated in 2001, this study reports results from years 4 and 5 of the experiment. Residue management effects were inconsistent among soil properties and years, and differences were generally agronomically non-significant. Averaged across irrigation treatments, soybean yield was unaffected by tillage, burning, and residue level either year. Within the non-irrigated treatment, conventionally tilled (CT) soybean yield was 38% greater ( p
  • Authors:
    • Tarkalson, D. D.
    • Shapiro, C. A.
    • Hergert, G. W.
    • Ferguson, R. B.
    • Dobermann, A. R.
    • Wortmann, C. S.
    • Walters, D. T.
  • Source: Agronomy Journal
  • Volume: 101
  • Issue: 3
  • Year: 2009
  • Summary: Nutrient management recommendations may change as yield levels and efficiency of crop production increase. Recommendations for P, K, and S were evaluated using results from 34 irrigated corn ( Zea mays L.) trials conducted in diverse situations across Nebraska. The mean yield was 14.7 Mg ha -1 with adequate fertilizer applied. The median harvest index values were 0.52, 0.89, 0.15, and 0.56 for biomass, P, K, and S, respectively. Median grain yields were 372, 49, and 613 kg kg -1 of aboveground plant uptake of P, K, and S, respectively. The estimated critical Bray-1 P level for corn response to 20 kg P ha -1 was 20 mg kg -1 when the previous crop was corn compared with 10 mg kg -1 when corn followed soybean [ Glycine max (L.) Merr.]. Soil test K was generally high with only three site-years
  • Authors:
    • Zhang, M. H.
    • Zhang, L. X.
    • Zhang, J. Q.
    • Watson, C.
  • Source: Acta Agronomica Sinica
  • Volume: 35
  • Issue: 2
  • Year: 2009
  • Summary: A study was conducted in Stoneville, Mississippi, USA, under irrigated conditions to develop predictive models, using a simple and effective model technique which can allow producers to predict soyabean growth and development stages in their fields. The models were constructed using 4-year field data (1998-2001) and validated with the fifth year data (2002). Potential factors affecting stages of soyabean growth and development were considered for developing the models. Affecting factors, such as weeds, insects, diseases and drought stress, were controlled optimally to simplify the modelling procedures. In addition, stepwise regression (SR) analysis, artificial neural networks (ANN), and interpolation approaches were used to construct the models. The modelling of soyabean growth and development processes was separated into 2 distinct periods: vegetative growth stage (V-stage) and reproductive growth stage (R-stage). The models included 10 V-stages (up to V8) and 8 R-stages. In the V-stages models, PD (planting date) and mean relative time-span for planting to a particular stage were the only significant parameters, whereas in R-stage models, PD and MG (maturity group) were significant. The models obtained accurate predictions were only using PD, MG and mean relative time-span from planting to a particular stage. The ANN method provided the greatest accuracy in predicting phenological events, indicating that the ANN method can be effectively applied in crop modelling.
  • Authors:
    • Andresen, D.
    • Das, S.
    • Miller, M.
    • Lauwo, S.
    • Staggenborg, S.
    • Jin, W.
    • Bulatewicz, T.
    • Peterson, J.
    • Steward, D. R.
    • Welch, S. M.
  • Source: Hydrology & Earth System Sciences
  • Volume: 13
  • Issue: 8
  • Year: 2009
  • Summary: Near-term consumption of groundwater for irrigated agriculture in the High Plains Aquifer supports a dynamic bio-socio-economic system, all parts of which will be impacted by a future transition to sustainable usage that matches natural recharge rates. Plants are the foundation of this system and so generic plant models suitable for coupling to representations of other component processes (hydrologic, economic, etc.) are key elements of needed stakeholder decision support systems. This study explores utilization of the Environmental Policy Integrated Climate (EPIC) model to serve in this role. Calibration required many facilities of a fully deployed decision support system: geo-referenced databases of crop (corn, sorghum, alfalfa, and soybean), soil, weather, and water-use data (4931 well-years), interfacing heterogeneous software components, and massively parallel processing (3.8*10 9 model runs). Bootstrap probability distributions for ten model parameters were obtained for each crop by entropy maximization via the genetic algorithm. The relative errors in yield and water estimates based on the parameters are analyzed by crop, the level of aggregation (county- or well-level), and the degree of independence between the data set used for estimation and the data being predicted.
  • Authors:
    • Changade, N. M.
    • Khodke, U. M.
    • Chavan, M. L.
  • Source: International Journal of Agricultural Engineering
  • Volume: 2
  • Issue: 2
  • Year: 2009
  • Summary: Historical weather data can be used to develop and modify the management practices to increase the production with the conjunctive use of rain and irrigation water as per the water needs of the crop. Regional scale crop and water resource planning needs determination of reference crop evapotranspiration (eto), probability distribution of rainfall and ETo, and estimates of magnitude and duration of water deficit and surplus which can promote crop production in both irrigated and dryland areas. Daily weather data of 16 years (from 1984 to 2001) for five locations i.e., Aurangabad, Beed, Nanded, Parbhani and Osmanabad of Marathwada region was used to determine reference crop evapotranspiration (ETo). The rainfall and ETo data were analysed to ascertain their fit to various probability distributions. The goodness of fit was determined by chi 2 tests. The developed crop coefficients were used to estimate crop water requirements of 8 major crops of the region. Effective rainfall was used to determine the weeks at which the rainfall exceed or fall deficit of crop water requirement. The study indicated that normal distribution gave the closest fit to the weekly rainfall and ETo data. The seasonal water requirement of cotton, groundnut, sugarcane and banana is higher at Parbhani whereas that of kharif sorghum, rabi sorghum, wheat and soybean is higher at Osmanabad than other places in the region, the effective rainfall meets the water need of kharif sorghum and soybean. The rainfall values during the critical growth stages of rabi (sorghum and wheat) and summer crops (groundnut, banana and sugarcane) are deficit than their water requirement in the respective weeks and hence require irrigation during those periods. Among the row crops, wheat and groundnut can only be grown under irrigation. Annual excess rainfall for various crops ranges between 561-749 mm for kharif sorghum, 124-195 mm for rabi sorghum, 0-15 mm for wheat, 624-808 mm for soybean, 633-786 mm for cotton, 453-609 mm for sugarcane and 526-703 mm for banana. If the excess rains are effectively harvested, the irrigation potential could be raised in the region.
  • Authors:
    • Madar, R.
    • Cosma, C.
    • Vuşcan, A.
    • Samuel, A. D.
    • Jurcă, A.
    • Ciobanu, G.
    • Domuta, C.
    • Ciobanu, C.
    • Albu, R.
    • Şandor, M.
  • Source: Bulletin of the University of Agricultural Sciences & Veterinary Medicine Cluj-Napoca
  • Volume: 66
  • Issue: 1
  • Year: 2009
  • Summary: The paper based on the research carried out during 2005-2008 in the long term trial placed in 1990 on the preluvosoil from Oradea. The monoculture of maize, maize-wheat and maize-soybean-wheat crop rotations were studied in unirrigated and irrigated conditions. The crop rotation of six years (oat+clover-clover-maize-wheat-maize-sunflower) was studied in unirrigated conditions. The research emphasized that the monoculture is the most responsible for the pest multiplication. In maize monoculture the larvae number on the roots was ranged between 4.91-8.23 and root attack degree in IOWA scale (with marks from 1 to 6 in which maximum attack is 6), had values between 3.84 and 5.62 and the frequent of attacked plants with the symptom "goose neck" ranged between 16,4% and 31.2% and larval aggressiveness being higher in the case of favorable soil moisture in irrigated condition. The maize rotation with other plants interrupts the biologic pest cycle. The results obtained emphasize that later maize sowing alongside by the utilizing of lower plant thickness level contribute to prevention of pest multiplication, while earlier sowing at high thickness favor the larvae developing.