• 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:
    • 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:
    • 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:
    • Zhang, J.
    • Liu, E.
    • Huang, X.
    • Chi, B.
    • Zhang, D.
  • Source: Transactions of the Chinese Society of Agricultural Engineering
  • Volume: 24
  • Issue: 4
  • Year: 2008
  • Summary: Field experiments were conducted in China to analyse the reasons for maize yield decrease under plastic film mulching condition. The results showed that plastic film mulching significantly increased soil temperature, promoted maize growth and significantly sped up phenostages of maize. However, maize encountered a serious summer drought at the heading stage. The normal pollination of maize was affected seriously, which resulted in the decrease of maize yield. Maize yields with plastic film mulching were 73.6 and 12.9% lower than that of open-ground planting for 2 consecutive years. The frequency of serious summer drought was 15.9% at the maize heading stage in the experiment area, which resulted in maize yield decrease. These facts should not be ignored and need investigating. So plastic film mulching should be rationally chosen and applied in semi-arid areas according to concrete conditions.
  • Authors:
    • Buck, R.
    • Hinz, C.
    • Murphy, D. V.
    • Butterbach-Bahl, K.
    • Gatter, D.
    • Kiese, R.
    • Barton, L.
  • Source: Global Change Biology
  • Volume: 14
  • Issue: 1
  • Year: 2008
  • Summary: Understanding nitrous oxide (N2O) emissions from agricultural soils in semi-arid regions is required to better understand global terrestrial N2O losses. Nitrous oxide emissions were measured from a rain-fed, cropped soil in a semi-arid region of south-western Australia for one year on a sub-daily basis. The site included N-fertilized (100 kg N ha-1 yr-1) and nonfertilized plots. Emissions were measured using soil chambers connected to a fully automated system that measured N2O using gas chromatography. Daily N2O emissions were low (-1.8 to 7.3 g N2O-N ha-1 day-1) and culminated in an annual loss of 0.11 kg N2O-N ha-1 from N-fertilized soil and 0.09 kg N2O-N ha-1 from nonfertilized soil. Over half (55%) the annual N2O emission occurred from both N treatments when the soil was fallow, following a series of summer rainfall events. At this time of the year, conditions were conducive for soil microbial N2O production: elevated soil water content, available N, soil temperatures generally >25 °C and no active plant growth. The proportion of N fertilizer emitted as N2O in 1 year, after correction for the "background" emission (no N fertilizer applied), was 0.02%. The emission factor reported in this study was 60 times lower than the IPCC default value for the application of synthetic fertilizers to land (1.25%), suggesting that the default may not be suitable for cropped soils in semi-arid regions. Applying N fertilizer did not significantly increase the annual N2O emission, demonstrating that a proportion of N2O emitted from agricultural soils may not be directly derived from the application of N fertilizer. "Background" emissions, resulting from other agricultural practices, need to be accounted for if we are to fully assess the impact of agriculture in semi-arid regions on global terrestrial N2O emissions.
  • Authors:
    • Kelly, K.
    • Armstrong, R.
    • Phillips, F.
    • Officer, S. J.
  • Source: 14th Australian Agronomy Conference
  • Year: 2008
  • Authors:
    • Ahuja, L. R.
    • Saseendran, S. A.
    • Ma, L.
    • Trout, T.
    • Nielsen, D. C.
  • Source: World Environmental and Water Resources Congress 2008
  • Year: 2008
  • Summary: Most of the agriculture in the Great Plains and western U.S. is water-limited, consisting of rain-fed, dry-land, cropping systems or range-livestock systems and some irrigated cropping systems where irrigation water is available. Prolonged drought in the last few years has aggravated the situation, and greater frequency of severe droughts predicted by global climate change models is a cause for great concern, especially for dry-land systems. At the same time, the increasing water demands for drinking, sanitation, urban irrigation, industry, and environmental uses are outbidding and reducing the irrigation water available for agriculture. Similar situation exists in many other arid to semi-arid parts of the world. To obtain maximum return out of limited rainfall and irrigation water, with minimum environmental impact, the producers need whole-system and quantitative management tools to help them optimize the use of available water and minimize associated inputs on site-specific and field-specific basis. The tools should help determine appropriate crop sequences, and optimize the use of limited rainfall and irrigation water with respect to the amounts and timings of rainfall, critical growth stages of crop, soil fertility, and weather conditions; help determine an optimal selection of alternate crops during droughts; and an optimal allocation of limited water among crops. There is currently great excitement about growing bio-energy crops in the area, including the dry-land oil seed crops and irrigated corn or other biomass crops. The above tools should also be able to evaluate the long-term economics of bio-energy crops while leaving enough crop residues on the soil to maintain soil organic matter.
  • Authors:
    • Bridges, M.
    • Henry, W. B.
    • Shaner, D. L.
    • Khosla, R.
    • Westra, P.
    • Reich, R.
  • Source: Journal of Environmental Quality
  • Volume: 37
  • Issue: 6
  • Year: 2008
  • Summary: An area of interest in precision farming is variable-rate application of herbicides to optimize herbicide use efficiency and minimize negative off-site and non-target effects. Site-specific weed management based on field scale management zones derived from soil characteristics known to affect soil-applied herbicide efficacy could alleviate challenges posed by post-emergence precision weed management. Two commonly used soil-applied herbicides in dryland corn ( Zea mays L.) production are atrazine and metolachlor. Accelerated dissipation of atrazine has been discovered recently in irrigated corn fields in eastern Colorado. The objectives of this study were (i) to compare the rates of dissipation of atrazine and metolachlor across different soil zones from three dryland no-tillage fields under laboratory incubation conditions and (ii) to determine if rapid dissipation of atrazine and/or metolachlor occurred in dryland soils. Herbicide dissipation was evaluated at time points between 0 and 35 d after soil treatment using a toluene extraction procedure with GC/MS analysis. Differential rates of atrazine and metolachlor dissipation occurred between two soil zones on two of three fields evaluated. Accelerated atrazine dissipation occurred in soil from all fields of this study, with half-lives ranging from 1.8 to 3.2 d in the laboratory. The rapid atrazine dissipation rates were likely attributed to the history of atrazine use on all fields investigated in this study. Metolachlor dissipation was not considered accelerated and exhibited half-lives ranging from 9.0 to 10.7 d in the laboratory.
  • Authors:
    • Fan, T.
    • Xu, M
    • Song, S.
    • Zhou, G.
    • Ding, L.
  • Source: Journal of Plant Nutrition and Soil Science
  • Volume: 171
  • Issue: 3
  • Year: 2008
  • Summary: Changes in grain yields and soil organic carbon (SOC) from a 26 y dryland fertilization trial in Pingliang, Gansu, China, were recorded. Cumulative C inputs from straw and root and manure for fertilizer treatments were estimated. Mean wheat ( Triticum aestivum L.) yields for the 18 y ranged from 1.72 t ha -1 for the unfertilized plots (CK) to 4.65 t ha -1 for the plots that received manure (M) annually with inorganic N and P fertilizers (MNP). Corn ( Zea mays L.) yields for the 6 y averaged 2.43 and 5.35 t ha -1 in the same treatments. Yields declined with year except in the CK for wheat. Wheat yields for N only declined with time by 117.8 kg ha -1 y -1 that was the highest decrease among all treatments, and that for NP declined by 84.7 kg ha -1 y -1, similar to the declines of 77.4 kg ha -1 y -1 for the treatment receiving straw and N annually and P every second year (SNP). Likewise, the corn yields declined highly for all treatments, and the declined amounts ranged from 108 to 258 kg ha -1 y -1 which was much higher than in wheat. These declined yields were mostly linked to both gradual dry weather and nutrients depletion of the soil. The N only resulted in both P and K deficiency in the soil, and soil N and K negative balances in the NP and MNP were obvious. Soil organic carbon (SOC) in the 0-20 cm soil layer increased with time except in the CK and N treatments, in which SOC remained almost stable. In the MNP and M treatments, 24.7% and 24.0% of the amount of cumulative C input from organic sources remained in the soil as SOC, but 13.7% of the C input from straw and root in the SNP, suggesting manure is more effective in building soil C than straw. Across the 26 y cropping and fertilization, annual soil-C sequestration rates ranged from 0.014 t C ha -1 y -1 for the CK to 0.372 t C ha -1 y -1 for the MNP. We found a strong linear relationship ( R2=0.74, p=0.025) between SOC sequestration and cumulative C input, with C conversion-to-SOC rate of 16.9%, suggesting these dryland soils have not reached an upper limit of C sequestration.
  • Authors:
    • Stevens, W. B.
    • Jabro, J. D.
    • Sainju, U. M.
  • Source: Journal of Environmental Quality
  • Volume: 37
  • Issue: 1
  • Year: 2008
  • Summary: Management practices can influence soil CO2 emission and C content in cropland, which can effect global warming. We examined the effects of combinations of irrigation, tillage, cropping systems, and N fertilization on soil CO2 flux, temperature, water, and C content at the 0- to 20-cm depth from May to November 2005 at two sites in the northern Great Plains. Treatments were two irrigation systems (irrigated vs. non-irrigated) and six management practices that contained tilled and no-tilled malt barley (Hordeum vulgaris L.) with 0 to 134 kg N ha-1, no-tilled pea (Pisum sativum L.), and a conservation reserve program (CRP) planting applied in Lihen sandy loam (sandy, mixed, frigid, Entic Haplustolls) in western North Dakota. In eastern Montana, treatments were no-tilled malt barley with 78 kg N ha-1, no-tilled rye (Secale cereale L.), no-tilled Austrian winter pea, no-tilled fallow, and tilled fallow applied in dryland Williams loam (fine-loamy, mixed Typic Argiborolls). Irrigation increased CO2 flux by 13% compared with non-irrigation by increasing soil water content in North Dakota. Tillage increased CO2 flux by 62 to 118% compared with no-tillage at both places. The flux was 1.5- to 2.5-fold greater with tilled than with non-tilled treatments following heavy rain or irrigation in North Dakota and 1.5- to 2.0-fold greater with crops than with fallow following substantial rain in Montana. Nitrogen fertilization increased CO2 flux by 14% compared with no N fertilization in North Dakota and cropping increased the flux by 79% compared with fallow in no-till and 0 kg N ha-1 in Montana. The CO2 flux in undisturbed CRP was similar to that in no-tilled crops. Although soil C content was not altered, management practices influenced CO2 flux within a short period due to changes in soil temperature, water, and nutrient contents. Regardless of irrigation, CO2 flux can be reduced from croplands to a level similar to that in CRP planting using no-tilled crops with or without N fertilization compared with other management practices.