• Authors:
    • Westfall, D.
    • Davis, J.
    • Reich, R.
    • Moshia, M.
    • Khosla, R.
  • Source: Proceedings of the 9th International Conference on Precision Agriculture
  • Year: 2008
  • Summary: Animal manure is a useful resource that could be recycled beneficially for crop production. When applied to the agricultural land, manure can increase grain yield and improve soil fertility. The objective of this study was to assess the influence of variable rate manure applications on grain yield under continuous maize ( Zea mays L.) fields across low, medium and high Management Zones (MZs) in dryland cropping systems. The study was conducted over two consecutive years in northeastern Colorado on a fine-loamy, mixed, mesic Aridic Haplustalfs soil. Treatments included (i) Variable and Constant yield goal manure treatments ranging from 22 to 67 Mg ha -1 and (ii) uniform application of synthetic N fertilizer based on soil testing. Experimental strips were 4.5 m wide and 540 m long spanned across MZs with treatments nested within MZs. Manure applications exhibited positive relationship with grain yield in site-year I (R 2=0.53) and site-year III (R 2=0.98), which were dryland fields in succeeding years. After two years of the on-going study, VYG and CYG manure treatments produced higher grain yield on low MZs as opposed to high MZs. The increased grain yield on low MZ in SY III was due to the increased level of organic matter, mineralized N and increase precipitation. Uniform application of synthetic N fertilizer has shown no improvement in the second year, producing lesser grain yield as opposed to VYG and CYG manure treatments on low producing MZ. Variable rate applications of manure have the potential to significantly enhance maize grain yield of low producing areas of the field. The study suggests that variable rate application of manure has potential to be used as an alternative to or in conjunction with synthetic N fertilizer for improving soil fertility and maintaining or improving grain yield. The key to precision manure management is to find a balance between agronomically and environmentally sound manure application rates across spatially variable soils. The good thing about manure application in dryland farming is that, there is little environmental pollution concern, more especially in semi-arid environment of northeastern Colorado.
  • Authors:
    • Rodriguez-del-Bosque, L.
    • Salinas-Garcia, J.
  • Source: Journal of Entomological Science
  • Volume: 43
  • Issue: 2
  • Year: 2008
  • Summary: The effects of tillage, irrigation (10 cm each at 10- to 14-leaf stage, and silking and milk stages, and no supplemental irrigation) and fertilizer (NPK at 0:0:0 or 140:40:0 kg/ha) treatments on the incidence of lepidopteran insects and fungi infesting maize (cv. Pioneer 3025W) were studied in Tamaulipas, Mexico, during 2005-07. The tillage treatments consisted of mouldboard ploughing (discing stalks after harvesting, followed by mouldboard ploughing, discing and row establishment), subsoil-bedding (shredding stalks after harvesting, followed by subsoiling on row centres and establishment of beds), shred-bedding (shredding stalks after harvesting, followed by bedding on old rows), and no-tillage (shredding stalks after harvesting, and spraying 0.6 kg glyphosate and 0.72 kg 2,4-D/ha twice for weed control). Mouldboard ploughing represented conventional tillage, whereas subsoil-bedding and shred-bedding were reduced tillage systems. The lepidopteran species recorded were Helicoverpa zea (86%) and Spodoptera frugiperda (14%). The incidence of these pests was highest in 2006 (91.5%) and lowest in 2007 (49.3%). The most common fungi were Fusarium spp., the highest incidence of which was registered in 2005 (24.4%). The incidence of Aspergillus flavus and Ustilago maydis [ U. zeae] was less than 4.0% regardless of the year. The incidence of lepidopterans significantly varied between the irrigation levels only (greater pest population under dryland farming). Fusarium spp. and A. flavus occurred more frequently under no-tillage compared with other tillage practices. The incidence of Fusarium spp. was higher in irrigated than in dryland maize.
  • Authors:
    • Ahuja, L. R.
    • Nielsen, D. C.
    • Trout, T. J.
    • Ma, L.
    • Saseendran,S. A.
  • Source: Water Resources Research
  • Volume: 44
  • Issue: 7
  • Year: 2008
  • Summary: Increasing competition for land and water resources due to increasing demands from rapid population growth calls for increasing water use efficiency of irrigated crops. It is important to develop location-specific agronomic practices to maximize water use efficiency (WUE). Adequately calibrated and validated agricultural systems models provide a systems approach and a fast alternative method for developing and evaluating agronomic practices that can utilize technological advances in limited irrigation agriculture. The objectives of this study were to (1) calibrate and validate the CERES-maize model under both dryland and irrigated corn ( Zea mays L.) production in northeastern Colorado and (2) use the model with a long-term weather record to determine (1) optimum allocation of limited irrigation between vegetative and reproductive growth stages and (2) optimum soil water depletion level for initiating limited irrigation. The soil series was a Rago silt loam, and the initial water content on 1 January of each year was equal to field capacity in the upper 300 mm and half of the field capacity below this depth. Optimum production and WUE with minimum nitrogen (N) losses were found when (1) a water allocation ratio of 40:60 or 50:50 (uniform) between vegetative and reproductive stages for irrigations up to 100 mm, and a ratio of 20:80 for irrigations above 100 mm was used; and (2) irrigation was initiated at 20% plant-available water (PAW) (80% depletion). When available water for irrigation is limited to 100 mm, irrigating 50% of the area with 200 mm of water at 20:80 split irrigations between the vegetative and reproductive stages produced greater yield than irrigating 100% of the area with 100 mm water. Concepts developed in the study can potentially be adapted to other locations, climates, and crops. However, precise site-specific recommendations need to be developed for each soil-climate zone using the validated system model.
  • Authors:
    • Rani, K. U.
    • Madhavi, M.
    • Ramesh, G.
    • Sankar, G. M.
    • Ravindrachary, G.
    • Adake, R. V.
    • Grace, J. K.
    • Korwar, G. R.
    • Mishra, P. K.
    • Srinivas, K.
    • Mandal, U. K.
    • Jain, P. M.
    • Jat, M. L.
    • Kothari, A. K.
    • Laddha, K. C.
    • Sharma, K. L.
  • Source: Indian Journal of Dryland Agricultural Research and Development
  • Volume: 23
  • Issue: 1
  • Year: 2008
  • Summary: Rainfed soils of Arjia region, Gujarat, India, which are under maize based production system, are damaged due to several soil related productivity constraints such as loss of topsoil causing severe soil erosion. The yield levels of majority of the crops grown in these soils are low. Soil quality deterioration has been the major bottleneck in realizing the higher levels of crop yields in this rainfed region. Hence, there was a need to identify and adopt appropriate soil and plant management practices that reduce soil degradation or maintain and improve soil quality at a desirable level. In view of the above, a long-term experiment was adopted for assessing soil quality as influenced by different soil-nutrient and other management practices followed at All India Coordinated Research Project for Dryland Agriculture centre of Arjia. Soil samples were analysed for 19 physical, chemical and biological soil quality parameters and soil quality indices were worked out using deviation method. From the viewpoint of soil quality improvement or soil aggradation, combination of conventional tillage + 2 weedicides + hoeing + 100% organic N ranked as superior among most treatment with the relative soil quality index value as high as 0.95 under maize-blackgram system. Further, cropping systems adjoining to the experimental station were also evaluated for soil quality. In the farmers' fields, the order of the systems in aggrading soil quality was as: maize-blackgram (1.00) > groundnut-sesame (0.75), > groundnut-taramira (0.72). The full paper deals in length about the extent and magnitude of changes in soil quality parameters and relative soil quality indices.
  • Authors:
    • Sharma, S. K.
    • Kothari, A. K.
    • Sharma, R. K.
    • Jain, P. M.
  • Source: Journal of Agrometeorology
  • Volume: 10
  • Issue: Special issue 1
  • Year: 2008
  • Summary: This paper draws on experiences with several participatory research activities carried out during 2005 and 2006 in the context of an Operational Research Project of All India Coordinated Research Project for Dryland areas carried out at the village Pathliyas situated in Mangarope watershed, Rajasthan, India. Data on the climatic constraints, drought and use of agro-advisory services from 45 households were collected to identify key track indicators for measuring community progress. The yield gap analysis of different crops in the watershed region presented indicated that technology gap existing between the potential and demonstrable yields was not substantial. Thus, it was possible to replicate the results obtained in research experiments in on-farm situation. The technology index varied from 20 to 47% which gave evidence that there was scope for further improvement in the productivity. The adoption of contingency plan for mitigating aberrant weather situation revealed that the adoption of different dryland technologies varied from 10 to 88%. During 2006-07, there was 30 days early onset of monsoon so sowing of maize and groundnut was forbidden based on land topography. Village survey result indicated that out of total cropped area (100 ha), maize and groundnut crops were sown on 35 and 10% of the area until the second week of June. Only 5% of the area was sown with the recommended agro-advisory services. However, the success rate of such farmers was not more than 10%. Thus, for higher sustainability, equality and stability of production, the agro-advisory services must be a vital component of action research and more emphasis should be given to capitalize on them.
  • Authors:
    • Dhuyvetter, K. C.
    • Staggenborg, S. A.
    • Gordon, W. B.
  • Source: Agronomy Journal
  • Volume: 100
  • Issue: 6
  • Year: 2008
  • Summary: Grain sorghum [ Sorghum bicolor (L.) Moench] is often grown where water stress is expected. But, improved drought tolerance in corn ( Zea mays L.) hybrids has resulted in increased dryland corn production in preference to grain sorghum. However, grain sorghum may still have a yield advantage over corn in drought prone environments. This study was conducted to determine if grain sorghum has either a yield or economic advantage over corn when drought or temperature stress occurs. Yield and weather data from crop performance testing programs in Kansas and Nebraska (1992-2005) were analyzed. Grain sorghum produced higher yields than corn in environments where corn yields were <6.4 Mg ha -1. When net returns ($ ha -1) were considered for grain sorghum prices that were set at 70, 87, 100, and 117% of corn prices, grain sorghum net returns were higher than corn net returns when corn yields were ≤4.4, 6.6, 8.8, and 13.6 Mg ha -1, respectively. Both corn and grain sorghum yields were positively correlated to June through August precipitation and negatively correlated to June through August maximum temperatures. The yield difference (grain sorghum minus corn) increased as July and August maximum temperatures increased. Monthly minimum temperatures affected corn yield less than grain sorghum yield. Producers in this region likely can minimize production risks by considering this historical yield information. At locations in this region where corn yields are consistently <6.4 Mg ha -1, producers should consider producing grain sorghum.
  • Authors:
    • Li, S.
    • Zhao, M.
    • Zhen, X.
    • Zhou, J.
    • Wang, C.
  • Source: Journal of Northwest A & F University - Natural Science Edition
  • Volume: 36
  • Issue: 1
  • Year: 2008
  • Summary: An experiment was conducted to investigate the effects of cultivation methods and N rates on N accumulation, distribution and utilization efficiency of winter wheat on manual loessial soils under the winter wheat-summer maize cropping rotation system. The treatments comprised 4 different cultivation methods, i.e. control (C), supplementary irrigation (SI), straw mulching (SM) and furrow planting (FP), and 3 N rates, i.e. 0, 120 and 240 kg/hm 2. Compared with the other 3 cultivation methods, the N residue in leaf and stem of wheat after harvesting was lower in the SI cultivation method, so was the rate of N residue to total N accumulation in the crop. However, the rate of N residue in grain to the N accumulated in shoot was increased. As the application rates of N increased, the N accumulation in leaf, stem, glume and rachis, and grain of wheat was significantly increased. When the N application was increased from 120 to 240 kg/hm 2, the N accumulation in wheat leaf, stem, and glume and rachis was increased after harvesting. However, the N accumulation in grain did not increased significantly. The application of N did not show significant effect on the distribution of N in the different organs of wheat. As the application rates of N increased, the N recovery, agronomic efficiency and physiological efficiency decreased. Compared with the other cultivation methods, the N recovery, agronomic efficiency and physiological efficiency of the SI pattern were higher during the 2 continuous years; the changes in the N efficiency indices of the other 3 cultivation methods varied in different years.
  • Authors:
    • Xia, J.
    • Wu, D.
    • Yu, Q.
    • Wang, E.
  • Source: International Journal of Climatology
  • Volume: 28
  • Issue: 14
  • Year: 2008
  • Summary: The North China Plain (NCP) is the largest agricultural production area in China. The extensive use of groundwater for irrigation agriculture under variable climatic conditions has resulted in the rapid decline of the groundwater table especially in areas north of the Yellow River, leading to hydrological imbalance and unsustainable agricultural production. This article analyses the sustainable level of vegetation/crop water use under the NCP climate by mimicking the evapotranspiration of a natural forest ecosystem. Such a system would have a mean annual evapotranspiration ranging from 470 mm/year in the northern to 910 mm/year in the southern part of the plain, leading to a mean annual water excess (rainfall minus evapotranspiration) ranging from 21 to 124 mm/year. The natural forest ecosystem would use less water than the current wheat/maize double cropping system. To mimic the water use of the natural system, dryland farming has to be practiced, and wheat and maize crops would have a water deficit of 90-435 and 0-257 mm/year, respectively. Under average conditions, this would mean that all the areas north of the 36 degrees N line have to abandon winter wheat production. Stopping irrigation will lead to significantly lower wheat yields (average yield 0.8 t/ha in the north to 5.2 t/ha in the south) and increased variability in wheat and maize yield both interannually and spatially. Better management practices, such as opportunity cropping (what and when to crop depending on climate and soil conditions rather than a set annual cycle), better use of climate forecast information to direct decision making, are required in order to achieve maximum return in good years while minimizing cost in bad years. Analysis on rainfall and potential evapotranspiration (PET) from 1961 to 2000 shows that there has been an increasing trend in crop water deficit in the northern part, but a decreasing trend in the southern part of the plain. It remains to be further studied whether this reflects long-term climate change or only a part of the climate variability.
  • Authors:
    • Egbert, S. L.
    • Wardlow, B. D.
  • Source: Remote Sensing of Environment
  • Volume: 112
  • Issue: 3
  • Year: 2008
  • Summary: Improved and up-to-date land use/land cover (LULC) data sets that classify specific crop types and associated land use practices are needed over intensively cropped regions such as the U.S. Central Great Plains, to support science and policy applications focused on understanding the role and response of the agricultural sector to environmental change issues. The Moderate Resolution Imaging Spectroradiometer (MODIS) holds considerable promise for detailed, large-area crop-related LULC mapping in this region given its global coverage, unique combination of spatial, spectral, and temporal resolutions, and the cost-free status of its data. The objective of this research was to evaluate the applicability of time-series MODIS 250 m normalized difference vegetation index (NDVI) data for large-area crop-related LULC mapping over the U.S. Central Great Plains. A hierarchical crop mapping protocol, which applied a decision tree classifier to multi-temporal NDVI data collected over the growing season, was tested for the state of Kansas. The hierarchical classification approach produced a series of four crop-related LULC maps that progressively classified: (1) crop/non-crop, (2) general crop types (alfalfa, summer crops, winter wheat, and fallow), (3) specific summer crop types (corn, sorghum, and soybeans), and (4) irrigated/non-irrigated crops. A series of quantitative and qualitative assessments were made at the state and sub-state levels to evaluate the overall map quality and highlight areas of misclassification for each map. The series of MODIS NDVI-derived crop maps generally had classification accuracies greater than 80%. Overall accuracies ranged from 94% for the general crop map to 84% for the summer crop map. The state-level crop patterns classified in the maps were consistent with the general cropping patterns across Kansas. The classified crop areas were usually within 1-5% of the USDA reported crop area for most classes. Sub-state comparisons found the areal discrepancies for most classes to be relatively minor throughout the state. In eastern Kansas, some small cropland areas could not be resolved at MODIS' 250 m resolution and led to an underclassification of cropland in the crop/non-crop map, which was propagated to the subsequent crop classifications. Notable regional areal differences in crop area were also found for a few selected crop classes and locations that were related to climate factors (i.e., omission of marginal, dryland cropped areas and the underclassification of irrigated crops in western Kansas), localized precipitation patterns (overclassification of irrigated crops in northeast Kansas), and specific cropping practices (double cropping in southeast Kansas).
  • Authors:
    • Nayyar, A.
    • Bijay, S.
    • Humphreys, E.
    • Brar, N.
    • Yadvinder, S.
    • Timsina, J.
  • Source: ACIAR Proceedings Series
  • Issue: 127
  • Year: 2008
  • Summary: Rice-wheat (RW) is the dominant cropping system in north-western India and is of immense importance for national food security. However, the sustainability of the RW system is threatened by water shortage and nutrient mining. Permanent bed RW systems with crop residue retention have been proposed as a means of reducing irrigation water use, improving soil properties and reducing the cost of crop establishment. A field experiment was conducted over 4 years in Punjab, India, to compare conventional and permanent bed RW cropping systems, with and without retention of crop residues, in terms of crop performance and nitrogen use efficiency (NUE). Two methods of rice establishment (transplanting and dry seeding) were included on both beds and flats with four N application rates (0, 80, 120, 160 kg N/ha). Rice grain yield increased significantly as N rate increased up to 160 kg N/ha irrespective of method of rice establishment. Puddled transplanted rice (PTR) was always superior to all other establishment methods in terms of biomass, yield and NUE. At 120 kg N/ha, yield of transplanted rice on permanent beds (TRB) was 29% lower than yield of PTR, while yield of direct-seeded rice on permanent beds (DSRB) was even lower (44% lower than yield of TRB). Wheat straw mulch further reduced yield of DSRB by 26% on average, but there was no effect of mulching on yield of TRB. Dry-seeded rice on flats and beds was prone to severe iron deficiency and root nematode infestation. Yield of DSRB relative to yield of PTR declined as the beds aged but there was no trend in relative yield of TRB. Recovery of fertiliser 15N in the straw plus grain was 30% in PTR compared with 14% for TRB and 17% for DSRB. The majority (65-83%) of the crop N uptake was derived from the soil in all treatments despite the application of urea at 120 kg N/ha. Total N losses from the urea N applied to rice ranged from 52% to 60% in TRB and DSRB compared with 38% in PTR. Wheat yield increased with N rate up to 120 kg N/ha, with further significant response to 160 kg N/ha in 2 of the 4 years. Wheat grain yield on permanent beds after TRB and DSRB was 75-96% of that of conventionally tilled wheat (CTW), with no trend in relative yield over time as the beds aged. Grain yield of wheat was similar in CTW and direct-drilled ('zero-till') wheat (DDW) on the flat. The 15N recovery in the wheat plants in all flat and bed treatments was similar. Straw mulch had no effect on yield or NUE of wheat. Recoveries of applied N in the wheat plants (27-38%) and soil (45-59%) were much higher than in rice. Total fertiliser N losses were much lower in wheat (mean 14-21%) compared with rice (mean 38-60%). After eight crops, soil organic C, total N and available K were significantly higher with straw mulch compared with no mulch. Permanent beds for RW seem to have limited potential under the soil and climatic conditions of Punjab, India, with current technology, even with full residue retention for both crops. Further research on permanent raised beds should focus on selection of rice and wheat cultivars that are better suited to beds; soil health issues such as nematodes and iron deficiency; weed control; N, water and residue management; and machinery development and practices.