• Authors:
    • Arf, O.
    • Sa, M.
    • Andreotti, M.
    • Buzetti, S.
    • Teixeira Filho, M.
  • Source: Ciencia Rural
  • Volume: 41
  • Issue: 8
  • Year: 2011
  • Summary: Proper management of nitrogen fertilization and using cultivars with high productive potential are essential to obtain high wheat yield. Thus, the objective of the present study was to assess the effects of different N doses and sources, one with a nitrification inhibitor, applied at sowing or as side dressing, on the production components and yield of two wheat cultivars irrigated, under no till, cultivated in a region of low altitude Cerrado (Selviria - MS). A randomized block design was used in a 5*3*2*2 factorial arrangement, that is, five nitrogen doses (0, 50, 100, 150 and 200 kg ha -1), three nitrogen sources (ammonium sulfonitrate with nitrification inhibitor (Entec), ammonium sulfate and urea) and two nitrogen application times (at sowing or side dressing) on two wheat cultivars ('E 22' and 'E 42') with three replications. There was no difference for grain yield between the wheat cultivars and among the nitrogen sources. The application of nitrogen totally at sowing is feasible as well as the traditional application at sowing and side dressing. The nitrogen doses increased the leaf N content of the 'E 22' cultivar, resulting in a reduction in the hectolitric mass of the 'E 42' cultivar and increased grain yield of the 'E 22' and 'E 42' wheat yield cultivars, respectively, up to doses of 126 and 122 kg ha -1 N, regardless of the application time and the nitrogen source.
  • Authors:
    • Uzun, B.
    • Furat, S.
    • Canakci, M.
    • Karayel, D.
    • Topakci, M.
  • Source: Applied Engineering In Agriculture
  • Volume: 27
  • Issue: 2
  • Year: 2011
  • Summary: The purpose of this research was to examine the performance of a modified vacuum seeder for hill drop sowing of sesame ( Sesamum indicum L.) following wheat ( Triticum aestivum) for no-till and reduced tillage farming. Tests were conducted during the growing seasons of 2008 and 2009 in the Bati Akdeniz Agricultural Research Institute's fields in Antalya, Turkey. A fluted coulter and double disc-type furrow opener were mounted on each unit of a common vacuum seeder. A seed plate modified to achieve hill-dropping of seeds was used in the metering mechanism of the seeder. Mean plant number per hill, coefficient of variation of plant number per hill, mean hill distance, coefficient of variation of hill distance, scattering distance ratio along the length of the row, sowing depth uniformity, and percent emergence of seeds and of hills were determined. Uniformity of hill spacing obtained from no-till plots was lower than from reduced and conventional tillage plots. Treatment effects were compared for three sesame seed varieties. No-till decreased the percent emergence of both seeds and hills for all varieties. The ranges of scattering distance ration and the coefficient of variation of hill distance were within the acceptable range of variability for all the tillage systems. In order to improve the emergence of individual seeds as well as of hills for no-till sowing of sesame, a more uniform sowing depth is needed. The conventional metering system of the seeder was sufficient for hill dropping of sesame seeds, but the performance of the soil engaging parts of the seeder was not satisfactory for no-till sowing. The negative effect of a high variation in sowing depth on percent emergence of seeds was obvious for no-till conditions. The general performance of the modified vacuum seeder was satisfactory for the reduced tillage system studied.
  • Authors:
    • Das, T. K.
    • Tuti, M. D.
  • Source: Indian Journal of Agronomy
  • Volume: 56
  • Issue: 2
  • Year: 2011
  • Summary: Effective weed control in no-till systems is mainly dependent on herbicides. Appropriate weed management strategies, however, can reduce the amount of herbicides. In this study possible weed management was attempted in wheat ( Triticum aestivum L. emend. Fiori & Paol.) under zero-tillage (without residue) and conventional tillage between 2006-07 and 2007-08 following residual effects of 13 weed control treatments with metribuzin applied during previous rainy ( kharif) seasons, 2006 and 2007 in soybean [ Glycine max (L) Mirrill]. The experiment was laid out in a split plot design with three replications. Total density of weeds did not differ significantly between weed control measures adopted during previous rainy season. But, conventional tillage (CT) caused a significant reduction in the populations of grass, broad-leaved (e.g., Chenopodium album L. and Melilotus indica L.) and total weeds when compared with zero-tillage (ZT) without crop residues. Similarly, higher nutrient removal by weeds was under zero-tillage than under conventional tillage. In general, residual effect of all the previous season metribuzin treatments was more pronounced on the grasses ( Phalaris minor Retz. and Avena sterilis ssp. ludoviciana Dur.) when compared with Chenopodium album and Melilotus indica. Wheat yield was similar in all previous season metribuzin treatments except in weed-free check in both years. However, metribuzin at 0.5 kg/ha pre-emergence, on yield, was more effective, indicating its considerable residual effect on weeds in wheat. This treatment also gave the highest net benefit:cost ratio.
  • Authors:
    • Flaten, D. N.
    • Entz, M. H.
    • Vaisman, I.
    • Gulden, R. H.
  • Source: Agronomy Journal
  • Volume: 103
  • Issue: 3
  • Year: 2011
  • Summary: The blade roller offers new opportunities to reduce tillage, especially in organic farming. The objective of the study was to reduce tillage in the green manure phase of a green manure-wheat ( Triticum aestivum L.) rotation by substituting tillage with blade rolling. A pea ( Pisum sativum L.) and oat ( Avena sativa L.) green manure was used for two site-years at Carman, MB, while a pea monocrop was used for one site-year at Oxbow, SK. At pea flowering, the green manure was terminated by rolling, tilling, or a combination of the two. Ammonia emissions were greater in the no-till compared with the tilled green manure system, though total ammonia losses were low (<13 kg ha -1). Replacing tillage with rolling reduced soil nitrate N in autumn after green manure by 56 to 88 kg ha -1 in the 0- to 60-cm soil depth. Reduced green manure tillage did not affect wheat establishment but delayed plant development in some instances. Fewer weeds were often observed in wheat in the no-till compared with tilled plots. Total N supply in the green manure-wheat system was reduced in the no-till system compared to the tilled only system at two out of three site-years by an average of 44%. While reduced N supply in the reduced tillage system coincided with reduced wheat yield and protein, it was concluded that factors other than N also were involved. Using the blade roller instead of tillage in the green manure year provides soil conservation benefits and facilitates wheat production the following year.
  • Authors:
    • Andreotti, M.
    • Benett, C. G. S.
    • Buzetti, S.
    • Valderrama, M.
    • Teixeira Filho, M. C. M.
  • Source: Pesquisa Agropecuaria Tropical
  • Volume: 41
  • Issue: 2
  • Year: 2011
  • Summary: Coated fertilizers can provide lower losses and higher soil nutrients availability, which can be absorbed by plants, when we consider their gradual release. The objective of this study was to evaluate the effect of doses and sources of N, P, and K on maize grain components and yield, under no-till system, in the Brazilian savannah. The experimental design was randomized blocks, with 4 top-dressed doses (0 kg ha -1, 40 kg ha -1, 80 kg ha -1, and 120 kg ha -1) and 2 sources (urea and coated urea), for N; 4 doses (0 kg ha -1, 50 kg ha -1, 100 kg ha -1, and 150 kg ha -1) and 2 sources (triple superphosphate and coated triple superphosphate), for P; and 4 doses (0 kg ha -1, 40 kg ha -1, 80 kg ha -1, and 120 kg ha -1) and 2 sources (potassium chloride and coated potassium chloride), for K, with 4 replications. The fertilizers coated with polymers (urea, triple superphosphate, and potassium chloride) were not efficient under the soil and climate conditions studied, because they provided results similar to the same conventional fertilizers, for the N, P, and K foliar contents, and irrigated maize grain components and yield. The increment of N doses increased linearly the N leaf content, number of ears per hectare and maize grains yield. The application of K 2O and P 2O 5 doses did not influence grain yield.
  • Authors:
    • Drury, C. F.
    • Carter, M. R.
    • Angers, D. A.
    • Janzen, H. H.
    • Ellert, B. H.
    • McConkey, B. G.
    • Bremer, E.
    • VandenBygaart, A. J.
    • Lafond, G. P.
    • McKenzie, R. H.
  • Source: Soil Science Society of America Journal
  • Volume: 75
  • Issue: 1
  • Year: 2011
  • Summary: The depth of sampling has recently been highlighted as critical to making accurate measurements of changes in SOC stocks. This paper aimed to determine the effects of land management changes (LMC) on soil organic carbon (SOC) by re-sampling long-term agoecosystem experiments (LTAEs) across Canada using identical sampling and laboratory protocols. The impact of sampling depth on the monitoring of LMC-induced differences in SOC stock in LTAEs in Canada, and the implications on statistical power and sampling design, were assessed. In most cases, four cores would be suitable for detecting a significant difference in SOC stock of 5 Mg ha -1 at 95% confidence for LMCs in western Canada. The impact of eliminating fallow on SOC stocks was typically restricted to the surface 15 cm. The impact of perennial forages on the average cumulative SOC was sufficiently large to be detectable at all sampling depths (to 60 cm). In three of the six LTAEs sampled in western Canada comparing conventional tillage to no-till, there was a significantly greater SOC storage in the 0- to 30-depth than the 0- to 15-cm depth, suggesting that sampling below 15 cm could be necessary. The same comparisons in eastern Canada suggested that sampling often must exceed the 30-cm depth to account for any changes in SOC due to moldboard plow tillage. Nonetheless, there was little evidence to suggest that increasing sampling intensity or sampling deeper would improve the ability to detect a difference in SOC stocks for this LMC.
  • Authors:
    • Torres, M. O.
    • Varennes, A. de
  • Source: Soil Use and Management
  • Volume: 27
  • Issue: 1
  • Year: 2011
  • Summary: Soil changes induced by crop rotations and soil management need to be quantified to clarify their impact on yield and soil quality. The objective of this study was to investigate the effect of continuous oat ( Avena sativa L.) and a lupin ( Lupinus albus L.)-oat rotation with and without tillage on soil enzymes, crop biomass and other soil properties In year 1, oat and lupin were grown in undisturbed plots or in plots subjected to disc tillage. Crop residues were incorporated before oat was sown in year 2 in the disc-tilled plots or remained on the soil surface of untilled plots. Soil samples were collected regularly and analysed for pH, organic C, Kjeldahl-N, mineral N, extractable P, and the enzyme activities of beta-glucosidase, cellulases, acid phosphatase, proteases, urease, and culturable bacteria and fungi. The main crop and tillage effects on soil parameters were: beta-glucosidase activity was greater after lupin than after oat, and the opposite was true for the number of culturable fungi. Organic carbon, phosphatase, cellulase and protease were greater in tilled soil than in the absence of tillage. Associations between variables that were stable over the 2 yr were those for mineral N and urease activity, cellulase activity and pH, and that of phosphatase activity and organic C. Our results contrast with most of the previous information on the effect of tillage on soil enzymes, where the activities were reported to be unchanged or decreased following tillage. This difference may be related to the small organic C content of the soil and to the fact that it was under fallow prior to the start of the experiment. In consequence, incorporation of residues would provide new sources of labile organic C for soil microbes, and result in increased enzymatic activity. The results obtained suggest that in coarse-textured soils poor in organic matter, tillage with residue conservation after a period of fallow rapidly improves several soil characteristics and should be carried out even if it were to be followed by a no-till system in the following years. This should be taken into consideration by land managers and technical advisers.
  • Authors:
    • Strickland, G. L.
    • Epplin, F. M.
    • Varner, B. T.
  • Source: Agronomy Journal
  • Volume: 103
  • Issue: 5
  • Year: 2011
  • Summary: The majority of cropland in the Southwest Oklahoma Agricultural Statistics District is tilled and seeded to continuous monoculture winter wheat (Triticum aestivum L.). This study was conducted to determine the expected yield and expected net returns of wheat, cotton (Gossypium hirsutum L.), and grain sorghum [Sorghum bicolor (L.) Moench], under two production systems, no-till (NT) and tilled (TL), and to determine the most risk-efficient system. The effect of tillage was investigated over 6 yr at Altus, OK, on a Hollister silty clay loam (fine, smectitic, thermic Typic Haplusterts) soil. Wheat and cotton yields were not different between tillage systems. Sorghum NT yielded significantly more than TL sorghum (P <= 0.05). Wheat NT produced the greatest expected net return to land, labor, overhead, and management ($217 ha(-1) yr(-1)). Tilled grain sorghum was the least profitable system (-$42 ha(-1) yr(-1)). Wheat NT required additional expenditures for herbicides ($15 ha(-1)), less for machinery fuel, lube, and repairs ($22 ha(-1)), and less ($23 ha(-1)) for machinery fixed costs. Net returns were slightly greater ($18 ha(-1)) for NT wheat than for TL wheat. However, since NT wheat yields were more variable, TL wheat may be preferred by risk-averse producers. Estimated machinery labor savings from switching from TL to NT wheat were 0.588 h ha(-1) or 609 h yr(-1) for a 1036 ha farm. The decision to switch from TL to NT wheat depends on risk preferences, and on the potential to use saved labor productively elsewhere, or to farm more land.
  • Authors:
    • Wilhelm, W. W.
    • Varvel, G. E.
  • Source: Soil & Tillage Research
  • Volume: 114
  • Issue: 1
  • Year: 2011
  • Summary: Emphasis and interest in carbon (C) and nitrogen (N) storage (sequestration) in soils has greatly increased in the last few years, especially C with its' potential to help alleviate or offset some of the negative effects of the increase in greenhouse gases in the atmosphere. Several questions still exist with regard to what management practices optimize C storage in the soil profile. A long-term rainfed study conducted in eastern Nebraska provided the opportunity to determine both the effects of different tillage treatments and cropping systems on soil N and soil organic C (SOC) levels throughout the soil profile. The study included six primary tillage systems (chisel, disk, plow, no-till, ridge-till, and subtill) with three cropping systems [continuous corn (CC), continuous soybean (CSB), and soybean-corn (SB-C)]. Soil samples were collected to a depth of 150-cm in depth increments of 0-15-, 15-30-, 15-30-, 30-60-, 60-90-, 90-120-, and 120-150-cm increments and composited by depth in the fall of 1999 after harvest and analyzed for total N and SOC. Significant differences in total N and SOC levels were obtained between tillage treatments and cropping systems in both surface depths of 0-15-, 15-30-cm, but also in the 30-60-cm depth. Total N and SOC accumulations throughout the profile (both calculated by depth and for equivalent masses of soil) were significantly affected by both tillage treatment and cropping system, with those in no-till the greatest among tillage treatments and those in CC the greatest among cropping systems. Soil N and SOC levels were increased at deeper depths in the profile, especially in those tillage systems with the least amount of soil disturbance. Most significant was the fact that soil N and SOC was sequestered deeper in the profile, which would strongly suggest that N and C at these depths would be less likely to be lost if the soil was tilled.
  • Authors:
    • Holan, S. H.
    • Goyne, K. W.
    • Veum, K. S.
    • Motavalli, P. P.
  • Source: Geoderma
  • Volume: 167-168
  • Year: 2011
  • Summary: Conservation management practices including upland vegetative filter strips (VFS) and no-till cultivation have the potential to enhance soil carbon sequestration and other ecosystem services in agroecosystems. A modified two-factor analysis of variance (ANOVA) with subsamples was used to compare SOC and TN on a concentration, soil volume and soil mass basis in claypan soils planted to different conservation management practices and as a function of landscape position. The three conservation management practices (no-till cultivation, grass VFS and agroforestry VFS) and four landscape positions (summit, shoulder, backslope and footslope) investigated were compared 10 years after VFS establishment in a no-till system planted to maize ( Zea mays. L.)-soybean ( Glycine max (L.) Merr.) rotation. Two soil depth increments (0-5 cm and 5-13 cm) were modeled separately to test for treatment effects. In the surface layer, mean SOC concentration was significantly greater in the VFS soils compared to no-till. On a soil volume or mass basis, no significant differences in SOC stocks were found among treatment means. Concentration and mass based TN values were significantly greater in the grass VFS relative to no-till in the surface layer. A rapid slaking stability test, developed to separate particulate, adsorbed and occluded organic carbon (PAO-C) and nitrogen (PAO-N), showed that VFS soils had significantly greater mean PAO-C and PAO-N concentrations, soil volume and soil mass based stocks than no-till. In addition, comparison of SOC:TN and PAO-C:PAO-N ratios suggest reduced decomposition and mineralization of SOC in the PAO fraction. No significant treatment effects were detected in total or PAO soil fractions in the subsurface layer or among landscape position in either depth increment. Study results emphasize the need to compare soil carbon and nitrogen stocks on a soil volume and/or soil mass basis using bulk density measurements. Additionally, the rapid PAO separation technique was found to be a good indicator of early changes in SOC and TN in the systems studied. Overall, this research indicates that grass VFS may sequester TN more rapidly than agroforestry VFS and that a greater proportion of SOC and TN may be stabilized in VFS soils compared to no-till.