• Authors:
    • Tetu, T.
    • Lea, P. J.
    • Dubois, F.
    • Hirel, B.
  • Source: Sustainability
  • Volume: 3
  • Issue: 9
  • Year: 2011
  • Summary: In this review, we present the recent developments and future prospects of improving nitrogen use efficiency (NUE) in crops using various complementary approaches. These include conventional breeding and molecular genetics, in addition to alternative farming techniques based on no-till continuous cover cropping cultures and/or organic nitrogen (N) nutrition. Whatever the mode of N fertilization, an increased knowledge of the mechanisms controlling plant N economy is essential for improving NUE and for reducing excessive input of fertilizers, while maintaining an acceptable yield and sufficient profit margin for the farmers. Using plants grown under agronomic conditions, with different tillage conditions, in pure or associated cultures, at low and high N mineral fertilizer input, or using organic fertilization, it is now possible to develop further whole plant agronomic and physiological studies. These can be combined with gene, protein and metabolite profiling to build up a comprehensive picture depicting the different steps of N uptake, assimilation and recycling to produce either biomass in vegetative organs or proteins in storage organs. We provide a critical overview as to how our understanding of the agro-ecophysiological, physiological and molecular controls of N assimilation in crops, under varying environmental conditions, has been improved. We have used combined approaches, based on agronomic studies, whole plant physiology, quantitative genetics, forward and reverse genetics and the emerging systems biology. Long-term sustainability may require a gradual transition from synthetic N inputs to legume-based crop rotation, including continuous cover cropping systems, where these may be possible in certain areas of the world, depending on climatic conditions. Current knowledge and prospects for future agronomic development and application for breeding crops adapted to lower mineral fertilizer input and to alternative farming techniques are explored, whilst taking into account the constraints of both the current world economic situation and the environment.
  • Authors:
    • Hu, H.
    • Tian, S.
    • Zhong, W.
    • Li, Z.
    • Ning, T.
    • Wang, Y.
    • Zhang, Z.
  • Source: Scientia Agricultura Sinica
  • Volume: 44
  • Issue: 9
  • Year: 2011
  • Summary: Objective: The objective of this study was to understand the effects of normal urea and controlled release urea on grain filling rate, yield and water use efficiency of different maize cultivars under different tillage modes. Method: Three sets of treatments were arranged in a split-split plot design. The whole-plot treatment factor was the tillage mode, stubble ploughing or subsoiling after stubble ploughing. The subplot treatment factor was maize cultivars Zhengdan 958 and Denghai 3. The sub-subplot treatment factor was the nitrogen level, including applied with 225 kg N.hm -2 normal urea, applied with 225 kg N.hm -2 controlled release urea, and no nitrogen fertilizer used as control. Result: At the same tillage mode, nitrogen level and maize cultivars, the soil water content in 0-100 cm soil layer applied with controlled release urea was higher at pre-tasselling stage, while lower at maturity stage than those applied with normal urea. It indicated that treatment applied with controlled release urea could realize higher use of soil water through time and space, and as a result increased the gain filling rate and water use efficiency. Subsoiling after stubble ploughing could also increase the grain filling rate and water use efficiency. Compared with Zhengdan 958, Denghai 3 had higher grain filling rate, yield and water use efficiency. And these were positive coupling effects between urea type, subsoiling, and maize cultivars, which was benefit for higher yield in dryland farm. Conclusion: Higher use of soil water through time and space and higher grain filling rate were the important reasons for higher yield and water use efficiency. Using suitable maize cultivars and applying controlled release urea, with subsoiling after stubble ploughing, could make the good use of soil water, and realize the space-time coincide between soil water supply and crop needs, which will be the important measures to achieve higher grain yield and higher benefit in semi-humid region of China.
  • Authors:
    • Klonsky, K. M.
    • Demoura, R.
    • Elkins, R. B.
    • Ingels, C. A.
    • Lanini, W. T.
    • Shackel, K. A.
  • Source: Acta Horticulturae
  • Issue: 909
  • Year: 2011
  • Summary: In 2009 and 2010, four weed control treatments (in-row mowing, landscape fabric, wood chips, and organic herbicide) and three fertilizer treatments (chicken manure at high vs. low rate and feather meal) were compared in an organic, no-till 'Bosc' pear ( Pyrus communis) orchard with solid-set sprinklers. Weed control in the landscape fabric and wood chip treatments was excellent, and multiple herbicide applications per year resulted in partial control. There were no significant yield differences among treatments, and little difference in fruit diameter or weight. There were no significant differences in trunk growth between treatments. The wood chip treatment had significantly lower stem water potential than other treatments in August 2009 only. In both years, the N content of leaves in mow+no fertilizer was significantly lower than most high-rate manure treatments, and leaf P content followed the opposite trend. Wood chips and fabric tended to have fewer vole holes than in-row mowing, and the herbicide treatment was intermediate. Assuming that landscape fabric lasts 8 years, it is only slightly more expensive per year than in-row mowing alone. An organic herbicide program is more expensive because of the herbicide cost and the many applications required. Wood chips were by far the most expensive treatment because of the cost of chips and spreading them, as well as the need to reapply every year. The use of a low rate of chicken manure was the cheapest fertilization strategy. Doubling that rate doubled the total costs, whereas the use of feather meal was about three times the cost of low-rate manure application for an equivalent amount of N.
  • Authors:
    • Jossi, W.
    • Zihlmann, U.
    • Heijden, M. van der
    • Anken, T.
    • Dorn, B.
  • Source: Agrarforschung Schwei
  • Volume: 18
  • Issue: 10
  • Year: 2011
  • Summary: Earthworm activity improves soil fertility. In arable crop rotations highest earthworm populations are usually found in leys. The impact of tillage system and tillage intensity on earthworm populations was studied in the two long term trials at Burgrain (Albertswil LU) and at Hausweid (Aadorf TG). At Burgrain having a crop rotation lasting six years and including a ley, no significant difference of earthworm biomass was found between ploughed plots and plots with in the sampling period 2004-2008 in the tillage system using minimum tillage (mulch drilling for oilseed rape and sowing with a rotary band cultivator rotary band seeding for silage maize) (IP extensive) compared to ploughing in both, the organic as well as the integrated production (IP intensive). In contrast, at Hausweid having a four years crop rotation at Hausweid without ley, earthworm populations differed significantly depending on tillage system and tillage intensity after 21 years of the trial. Earthworm biomass reached 330 g per m 2 in the permanent grassland adjacent to the trial whereas it was reduced by 50% in the no-till and even by 80% in the ploughed plots. Additionally, average earthworm species diversity in permanent grassland and no-till was 30% higher than in ploughed tillage system. These findings confirm the positive impact of no-till on the increase of earthworm populations and species diversity.
  • Authors:
    • Kaspar, T. C.
    • Parkin, T. B.
  • Source: Soil Science Society of America Journal
  • Volume: 75
  • Issue: 6
  • Year: 2011
  • Summary: Measurements of soil CO 2 flux in the absence of living plants can be used to evaluate the effectiveness of soil management practices for C sequestration, but field CO 2 flux is spatially variable and may be affected by soil compaction and the percentage of total pore space filled with water (%WFPS). The objectives of our study were: (i) to evaluate the effect of wheel traffic compaction on CO 2 flux at two landscape positions with differing soil properties; and (ii) to examine the relationship of CO 2 flux and %WFPS under field conditions and a wide range of soil porosities. Carbon dioxide flux was measured near Ames, IA, in a no-till system without living plants using the closed chamber method on nine cylinders inserted into the soil at each measurement site and evenly spaced across three rows, an untracked interrow, and a tracked interrow. Flux, volumetric water contents, and soil temperature were measured on 12 or 13 d between day of the year (DOY) 164 and 284 in 2001, 2004, and 2005. Bulk density, soil organic C concentration, and soil texture were determined after DOY 284. On most days, CO 2 flux was less in the tracked interrow than in the row or untracked interrow positions. In all 3 yr, the cumulative flux of the tracked position was significantly less than one or both of the other positions. Landscape position did not affect the response of CO 2 flux to traffic. Percentage water-filled pore space was not a good predictor of surface CO 2 flux in the field. The effect of wheel traffic compaction on CO 2 flux should be considered when soil CO 2 flux is used to compare management practices.
  • Authors:
    • Kihara, J.
    • Bationo, A.
    • Mugendi, D. N.
    • Martius, C.
    • Vlek, P. L. G.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 90
  • Issue: 2
  • Year: 2011
  • Summary: Smallholder land productivity in drylands can be increased by optimizing locally available resources, through nutrient enhancement and water conservation. In this study, we investigated the effect of tillage system, organic resource and chemical nitrogen fertilizer application on maize productivity in a sandy soil in eastern Kenya over four seasons. The objectives were to (1) determine effects of different tillage-organic resource combinations on soil structure and crop yield, (2) determine optimum organic-inorganic nutrient combinations for arid and semi-arid environments in Kenya and, (3) assess partial nutrient budgets of different soil, water and nutrient management practices using nutrient inflows and outflows. This experiment, initiated in the short rainy season of 2005, was a split plot design with 7 treatments involving combinations of tillage (tied-ridges, conventional tillage and no-till) and organic resource (1 t ha -1 manure + 1 t ha -1 crop residue and; 2 t ha -1 of manure (no crop residue) in the main plots). Chemical nitrogen fertilizer at 0 and 60 kg N ha -1 was used in sub-plots. Although average yield in no-till was by 30-65% lower than in conventional and tied-ridges during the initial two seasons, it achieved 7-40% higher yields than these tillage systems by season four. Combined application of 1 t ha -1 of crop residue and 1 t ha -1 of manure increased maize yield over sole application of manure at 2 t ha -1 by between 17 and 51% depending on the tillage system, for treatments without inorganic N fertilizer. Cumulative nutrients in harvested maize in the four seasons ranged from 77 to 196 kg N ha -1, 12 to 27 kg P ha -1 and 102 to 191 kg K ha -1, representing 23 and 62% of applied N in treatments with and without mineral fertilizer N respectively, 10% of applied P and 35% of applied K. Chemical nitrogen fertilizer application increased maize yields by 17-94%; the increases were significant in the first 3 seasons ( P2 mm) and micro-aggregates fractions (53 m: P tied-ridges > conventional tillage. Also, combining crop residue and manure increased large macro-aggregates by 1.4-4.0 g 100 g -1 soil above manure only treatments. We conclude that even with modest organic resource application, and depending on the number of seasons of use, conservation tillage systems such as tied-ridges and no-till can be effective in improving crop yield, nutrient uptake and soil structure and that farmers are better off applying 1 t ha -1 each of crop residue and manure rather than sole manure.
  • Authors:
    • Kocyigit, R.
    • Rice ,C. W.
  • Source: Bulgarian Journal of Agricultural Science
  • Volume: 17
  • Issue: 4
  • Year: 2011
  • Summary: The soil surface CO 2 flux is the second largest flux in the terrestrial carbon budget after photosynthesis. Plant root and microbial respiration produce CO 2 in soils, which are important components of the global C cycle. This study determined the amount of CO 2 released during spring wheat ( Triticum aestivum L.) growth under no-till (NT) and conventional tillage (CT) systems. This experiment was conducted at Kansas State University North Agronomy Farm, Manhattan, KS, on a Kennebec silt loam. This study site was previously under dry land continuous corn production with NT and CT for more than 10 years. Spring wheat ( Triticum aestivum L.) was planted with two tillage systems (NT and CT) as four replicates in March. Surface CO 2 flux was measured weekly during plant growth. Soil water content at the surface (5 cm) tended to be greater in NT and decreased from planting to harvest. Soil microbial activity at the surface was usually higher in NT and decreased from planting to harvest, while activity was constant in the deeper depths. The higher microbial activity at the surface of NT occurred after 60 days of planting where soil water content was the most limiting factor on microbial activity. Soil CO 2 flux varied in response to changes in soil water content and the variation and magnitude of the increase was greater at higher soil water contents. Conventional tillage released 20% more CO 2 to the atmosphere compare to NT after 10 years in the North American Great Plains Regions.
  • Authors:
    • Kutcher, H. R.
    • Johnston, A. M.
    • Bailey, K. L.
    • Malhi, S. S.
  • Source: Field Crops Research
  • Volume: 124
  • Issue: 2
  • Year: 2011
  • Summary: The impact of tillage system, rotation sequence and foliar fungicides on diseases and seed yield and quality of wheat, barley, pea, canola and flax was determined in the second cycle of three, 4-year rotations from 1998 to 2001 on a Black Chernozem (Udic Boroll) at Melfort, Saskatchewan, Canada. The objective of the study was to evaluate the impact of reduced-tillage production systems, broadleaf cropping intensity and fungicide use on cereal, oilseed and pulse crops in northeastern Saskatchewan, a sub-humid region of the northern Great Plains. A split-split plot design was used with three tillage systems (conventional, minimum and no-till) as main plots, three rotations of increasing broadleaf crop intensity (1. canola-wheat-barley-barley; 2. canola-barley-pea-wheat; and 3. canola-pea-flax-barley) as sub-plots, and fungicide treatments (treated or untreated) as sub-sub-plots. Fungicides appropriate for the diseases of concern were applied at recommended crop development stages and application rates, followed by assessment of diseases. Tillage system had little impact on diseases of any crop, although seed yield was usually greater under no-till for most crops under dry conditions. Rotation was not a major factor in disease severity of most of the crops, except barley in the rotation where it was grown for two consecutive years. Under dry conditions, barley yield was reduced when it followed flax compared with other crops, most likely due to less available soil moisture after flax. Fungicide application had the greatest impact on disease control and seed yield increase, although results varied among crops and years. In conclusion, the findings indicate that tillage system had little effect on disease severity, rotation contributed to greater disease severity only when a crop was grown intensively, such as on its own stubble, and fungicide application had variable effects on both disease control and seed yield.
  • Authors:
    • Walley, F.
    • May, W. E.
    • Holzapfel, C. B.
    • Lafond, G. P.
  • Source: Soil & Tillage Research
  • Volume: 117
  • Year: 2011
  • Summary: Meeting the needs of an increasing population requires protection of our arable land base and improvements in productivity. The study compared soil quality characteristics and crop yield to nitrogen (N) fertilizer in two adjacent fields; one field managed with no-till for 31 years while the other for 9 years. In 2003, the two fields along with native prairie were sampled for soil quality parameters across two landscape positions. A small plot study involving five rates of urea N (0, 30, 60 90 and 120 kg N ha -1) and two phosphorus fertilizer placement methods (seed-placed vs side-banded) was conducted on the two adjacent fields for the period 2002-2009. The rates of N were superimposed on the same plots each year whereas wheat and canola were normally grown in alternate years. An N balance was conducted after 8 years to account for inputs and outputs of N. Soil bulk density values were 0.98 g cm -3 for native prairie and 1.46 for LTNT and STNT in the 0-15 cm soil layer. The native prairie had 48.2 t ha -1of SOC vs 44.4 and 36.7 for LTNT and STNT, respectively, in the 0-15 cm soil layer and no detectable differences for the 15-30 cm soil layer in 2003. Potentially mineralizable N using the Hot KCl digestion in the 0-15 cm soil layer was 60 kg ha -1 of ammonium nitrogen for native prairie and 30 and 22 kg ha -1 for LTNT and STNT, respectively. For amino sugar-N, native prairie had 558 kg ha -1 vs 462 and 370 kg ha -1 for the LTNT and STNT, respectively. This indicates a positive relationship between SOC levels measured and potentially mineralizable N reflecting differences in land management. Phosphorus fertilizer placed in the side-band with N yielded 3.5% more than seed-placed phosphorus in spring wheat and no difference in canola. Grain yields were 14% and 16% more for LTNT than STNT in spring wheat and canola, respectively. Maximum grain N removal averaged in wheat was 87 kg ha -1 for LTNT and 74 kg ha -1 for STNT and 71 and 65.4 kg ha -1 in canola, respectively. A positive N balance was obtained provided that 60 kg ha -1 of N was applied every year and no accumulation of nitrate-N was noted even with rates that exceeded N removal in the grain. This supports the view that no-till combined with continuous cropping and proper fertility represents a path to sustaining the global soil resource.
  • Authors:
    • Lal, R.
  • Source: Food Policy
  • Volume: 36
  • Issue: S1
  • Year: 2011
  • Summary: Soils of the world's agroecosystems (croplands, grazing lands, rangelands) are depleted of their soil organic carbon (SOC) pool by 25-75% depending on climate, soil type, and historic management. The magnitude of loss may be 10 to 50 tons C/ha. Soils with severe depletion of their SOC pool have low agronomic yield and low use efficiency of added input. Conversion to a restorative land use and adoption of recommended management practices, can enhance the SOC pool, improve soil quality, increase agronomic productivity, advance global food security, enhance soil resilience to adapt to extreme climatic events, and mitigate climate change by off-setting fossil fuel emissions. The technical potential of carbon (C) sequestration in soils of the agroecosystems is 1.2-3.1 billion tons C/yr. Improvement in soil quality, by increase in the SOC pool of 1 ton C/ha/yr in the root zone, can increase annual food production in developing countries by 24-32 million tons of food grains and 6-10 million tons of roots and tubers. The strategy is to create positive soil C and nutrient budgets through adoption of no-till farming with mulch, use of cover crops, integrated nutrient management including biofertilizers, water conservation, and harvesting, and improving soil structure and tilth.