• Authors:
    • Torabi-Sirchi, M. H.
    • Saffari, M.
  • Source: American-Eurasian Journal of Agricultural & Environmental Science
  • Volume: 10
  • Issue: 2
  • Year: 2011
  • Summary: Allelopathy is a procedure in which secondary metabolites produced by plants, micro-organisms, viruses and fungi, control growth and development of other biological systems. Some plants may beneficially or antagonistically affect other plants through allelochemical compounds which may be released directly or indirectly from live or dead parts and cause allelopathic and phytotoxic effects. In Kerman (located in the South East of Iran) cultivating corn after winter wheat usually causes less growth and yield. This study was conducted to estimate the effects of different concentrations of two native Iranian wheat (Alvand and Falat) straw extracts on germination, radicle growth, coleoptile length, plant height, leaf area (LA), wet weight (WW) and dry weight (DW) of two hybrid corn varieties (single cross 704 and single cross 647). Results show that the straw extracts, have negative and significant effects on both corn varieties' growth and the significant allelopathic effects remained up to 90 days after wheat harvest; but decreased gradually up to 180 days after harvest. Base on the study results, we advise that before corn cultivation, wheat straw and residues should be eliminated from the field to avoid negative allelopathic effects of wheat straw on corn growth. Hence, it is recommended to let no-till fields as fallow for 6 months; to acquire convenient growth and high yield for corn.
  • Authors:
    • Samuel, A.
    • Domuta, C.
    • Sandor, M.
    • Vuscan, A.
    • Brejea, R.
  • Source: Romanian Agricultural Research
  • Issue: 28
  • Year: 2011
  • Summary: Long-term field trials can provide important information about the effects of soil management practices on soil properties but there are relatively few such trials available. The Agricultural Research and Development Station in Oradea (Bihor county) provided opportunity to study the effects of 18 years of cultivation on preluvosoil. The objective of the reported work was to determine at this site the effects of soil management practices on phosphatase activities as an index of soil biology. Phosphatase (phosphomonoesterase) activities were determined for two years, from 2008 to 2009, in the 0-20, 20-40 and 40-60 cm layers of a preluvosoil, from a long term trials with various tillage practices (no-till and conventional tillage), crop rotation (2 and 6 crop rotations) and fertilization [mineral (NP) fertilization and farmyard-manuring] experiment. The determined activities decreased with increasing sampling depth. No-till - in comparison with conventional tillage - resulted in significantly higher soil phosphatase activities in the 0-20 and in significantly lower activities in the deeper layers. The soil under maize or wheat was more enzyme-active in the 6 than in the 2 crop rotation. In the 2 crop rotation, higher phosphatase activities were recorded under wheat than under maize. Farmyard-manuring of maize - in comparison with mineral (NP) fertilization - led to a significant increase in enzyme activities. Maintenance of enzyme activities over tens of years in agricultural soils is partly attributed to traditional management practices including rotations with legumes, additions of animal manures, and minimum tillage.
  • Authors:
    • Santos, H.
    • Fontaneli, R.
    • Spera, S.
    • Dreon, G.
  • Source: Revista Brasileira de Ciencias Agrarias
  • Volume: 6
  • Issue: 3
  • Year: 2011
  • Summary: Soil fertility attributes were evaluated on a typical dystrophic Red Latosol (typic Haplorthox) located in Passo Fundo, State of Rio Grande do Sul, Brazil, twelve years after the establishment (1993, 2000, 2002 and 2005) of five integrated crop/livestock farming production systems: system I - wheat/soybean, white oat/soybean, and common vetch/corn; system II - wheat/soybean, white oat/soybean, and grazed black oat+grazed common vetch/corn; system III - perennial cool season pastures (fescue+white clover+red clover+birds foot trefoil); system IV - perennial warm season pastures (bahiagrass+black oat+rye grass+white clover+red clover+birds foot trefoil); and system V - alfalfa as hay crop. The plots under systems III, IV, and V returned to system I after the summer of 1996. However, in the summer of 2002, in the systems III, IV and V, what used to be crop returned to pasture and what used to be pasture returned to crop. An acidification process occurred in all layers by the lowest pH values and higher concentration and saturation by Al, in comparison to the soil in 1998. The organic matter level and the P, K and Al levels increased between 1998 to 2002, in all sampled layers, while the opposite occurred with pH, Ca and Mg contents.
  • Authors:
    • Pauletti, V.
    • Piva, J.
    • Santos, N.
    • Dieckow, J.
    • Bayer, C.
    • Molin, R.
    • Favaretto, N.
  • Source: Soil & Tillage Research
  • Volume: 111
  • Issue: 2
  • Year: 2011
  • Summary: To improve C sequestration in no-till soils requires further development of crop rotations with high phytomass-C additions. The objectives of this study were (i) to assess long-term (17 years) contributions of cover crop- or forage-based no-till rotations and their related shoot and root additions to the accumulation of C in bulk and in physical fractions of a subtropical Ferralsol (20-cm depth); and (ii) infer if these rotations promote C sequestration and reach an eventual C saturation level in the soil. A wheat ( Triticum aestivum L., winter crop)-soybean ( Glycine max (L.) Merr, summer crop) succession was the baseline system. The soil under alfalfa ( Medicago sativa L., hay forage) intercropped every three years with maize ( Zea mays L., summer crop) had the highest C accumulation (0.44 Mg C ha -1 year -1). The bi-annual rotation of ryegrass ( Lolium multiflorum Lam., hay winter forage)-maize-ryegrass-soybean had a soil C sequestration of 0.32 Mg C ha -1 year -1. Among the two bi-annual cover crop-based rotations, the vetch ( Vicia villosa Roth, winter cover crop)-maize-wheat-soybean rotation added 7.58 Mg C ha -1 year -1 as shoot plus root and sequestered 0.28 Mg C ha -1 year -1. The counterpart grass-based rotation of oat ( Avena strigosa Schreb., winter cover crop)-maize-wheat-soybean sequestered only 0.16 Mg C ha -1 year -1, although adding 13% more C (8.56 Mg ha -1 year -1). The vetch legume-based rotation, with a relative conversion factor (RCF) of 0.147, was more efficient in converting biomass C into sequestered soil C than oat grass-based rotation (RCF=0.057). Soil C stocks showed a close relationship ( R2=0.72-0.98, P<0.10) with root C addition, a poor relationship with total C addition and no relationship with shoot C addition. This suggests a more effective role of root than shoot additions in C accumulation in this no-till soil. Most of the C accumulation took place in the mineral-associated organic matter (71-95%, in the 0-5 cm layer) compared to the particulate organic matter. The asymptotic relationship between root C addition and C stocks in bulk soil and in mineral-associated fraction supports the idea of C saturation. In conclusion, forages or legume cover crops contribute to C sequestration in no-till tropical Ferrasols, and most of this contribution is from roots and stored in the mineral-associated fraction. This combination of soil and rotations can reach an eventual soil C saturation.
  • Authors:
    • Scherer, E. E.
  • Source: Agropecuaria Catarinense
  • Volume: 24
  • Issue: 2
  • Year: 2011
  • Summary: Organic agriculture in no-till system requires a new set of producer skills especially in the area of soil fertility and fertilizer use. In a field experiment in organic system in Chapeco, SC, Southern Brazil, the effect of different organic fertilizers (poultry dry litter, swine deep litter, swine composted manure, cattle composted manure and liquid swine manure) on the corn and common been yields was investigated. The organic fertilizers were scattered on the soil surface in the no-till system on the day of the sowing of common bean and corn. The solid manure was applied at 5 and 10 t/ha, dry weight, and the liquid manure at 30 and 60 m 3/ha for common beans and corn, respectively. A completely randomized block experimental design with six replications was used. The utilization of solid and liquid organic manure increased the grain yield of both cultures in all six years. Common beans and corn grain average yield with organic fertilizers use was 30% and 54% greater than yield without fertilizer, respectively. Solid swine manure and organic compost had a better performance on common bean grain yield, and liquid swine manure on corn yield.
  • Authors:
    • Jones, B. P.
    • Sequeira, C. H.
    • Alley, M. M.
  • Source: Soil Biology and Biochemistry
  • Volume: 43
  • Issue: 2
  • Year: 2011
  • Summary: Particulate organic matter (POM) and light fraction (LF) organic matter are potentially labile (active) fractions of soil organic matter (SOM) that have been shown to be indicators of short-term changes in soil management practices (e.g. tillage, manure and fertilizer applications, and crop rotation). These two fractions consist mainly of partially decomposed plant residues, microbial residues, seeds, and spores forming organo-mineral complexes with soil mineral particles; however, they cannot be used as synonyms because of their different chemical composition and structure. Particulate-OM is recovered by size-based procedures while LF is generally recovered in two distinct fractions [free-LF (FLF) and occluded-LF (OLF)] using density-based solutions in conjunction with soil-aggregate disruption. Solutions used in these density-based separations have most commonly varied in density from 1.6 to 2.0 g cm -3. Sodium iodide (NaI) and sodium polytungstate (SPT) are the chemicals most often used to prepare the density solutions in LF recovery but comparisons of the effectiveness of two solutions have not been conducted. The objectives of this research were: (1) compare the efficiency of similar density solutions of NaI and SPT in recovering FLF; and (2) compare POM, FLF, and OLF as possible sensitive indices of short-term soil changes due to tillage management. Soil samples were collected at 0-15 cm depth from a cropping system experiment conducted on a silt loam Ultisol. Plots selected for sampling had received either reduced till (RT) or no-till (NT), and cropping was continuous corn silage for a period of 3 years prior to sampling. Solutions of NaI and SPT at densities of 1.6 and 1.8 g cm -3 were used to recover FLF, and OLF was recovered with SPT solution at a density of 2.0 g cm -3 from the soil pellet remaining after FLF recovery with SPT 1.6 g cm -3. The average total soil organic carbon (SOC) content of these samples was of 12.7 g kg -1, and carbon-POM (C-POM), carbon-FLF (C-FLF), and carbon-OLF (C-OLF) represented 22.4, 5.5, and 5.2% of it, respectively. In general, C-FLF and nitrogen-FLF (N-FLF) contents recovered did not differ significantly between chemical solutions (NaI or SPT) adjusted to the same density (1.6 or 1.8 g cm -3). Increasing the density within a specific solution (NaI or SPT) resulted in significantly higher C-FLF and N-FLF recovery. For instance, C-FLF recovery averaged 637 and 954 mg kg -1 at 1.6 and 1.8 g cm -3, respectively. For both chemicals increasing density from 1.6 to 1.8 g cm -3 reduced the variability in recovering C-FLF and N-FLF with coefficient of variation values decreasing from a range of 14.9-19.1% for densities of 1.6 g cm -3 to 6.7-10.4% when densities increased to 1.8 g cm -3. In the present work, POM and OLF were more sensitive than FLF to changes in tillage management, with significantly greater amounts of the sensitive fractions in RT samples. A better sensitivity of FLF would be expected if treatments dealing with residue input (e.g. crop rotation and cover crop) were evaluated.
  • Authors:
    • Sequeira, C. H.
    • Alley, M. M.
  • Source: Soil Science Society of America Journal
  • Volume: 75
  • Issue: 5
  • Year: 2011
  • Summary: Soil organic matter (SOM) is commonly used as an indicator of soil quality, with different fractions being used as indices to measure changes in SOM caused by management. The objective of this study was to compare whether selected SOM fractions exhibited sensitivity to short-term changes in management. The experiment was conducted for similar to 3 yr as a split-split-plot design with crop rotation as the whole-plot treatment factor, tillage as the subplot treatment factor, and cover crop management as the sub-subplot treatment factor. Soil samples were collected at the 0- to 15-cm depth. Soil organic C (SOC) and N, particulate organic matter (POM), free light fraction (FLF), Illinois soil N test (ISNT), and easily oxidizable C (EOC) were tested as possible sensitive indices to changes in management. The stable fraction SOC was only affected by cover crop management, while C and N contents and C/N ratio of the labile POM and FLF fractions were affected by additional management practices. Between POM and FLF, the latter was the most sensitive, with cover crop management having the greatest effect. Because FLF is chemically and structurally closer to plant residues than POM, the sensitivity rank position of these fractions would probably be at least more similar if only tillage management was considered. In addition, the lack of sensitivity of ISNT and EOC to any tested management practice is added to previous studies that have raised questions of the representation of the labile SOM pool through these fractions.
  • Authors:
    • Singh, R.
    • Sharma, A. R.
    • Dhyani, S. K.
    • Dube, R. K.
  • Source: Journal of Crop Improvement
  • Volume: 25
  • Issue: 4
  • Year: 2011
  • Summary: Mulching is highly beneficial for resource conservation under rainfed conditions, but non-availability of organic biomass and easy availability of fertilizers and herbicides has led to a gradual discontinuation of this practice. Various vegetative materials, including some troublesome weedy perennials, are available locally, which can be recycled for enhanced soil moisture and nutrient conservation. A field experiment was conducted at Dehradun, India, from 2001-2004 to study the effect of mulching with kudzu ( Peuraria hirsuta), wild sage ( Lantana camara), and subabul ( Leucaena leucocephala) applied at 30 and 60 days of growth of maize ( Zea mays), maize harvest, and sowing of wheat ( Triticum aestivum). Application of 10 t/ha (fresh biomass) added 1.6-2.3 t dry matter through Peuraria, 2.5-3-2 t through Lantana, and 2.9-3-9 t/ha through Leuceana, which contributed 47.7-60.9 kg N, 58.4-70.9 kg N, and 118.4-148.4 kg N/ha, respectively. All mulching materials were beneficial and improved productivity of maize significantly by 16.6-20.6% over no mulching. Wheat yield also increased because of mulching in previous maize (+11.2%), and the beneficial effect was relatively greater (12.4-25.1%) when mulching was done at maize harvest or wheat sowing. Mulching showed improvement in organic C and total N status, and a decrease in bulk density associated with an increase in infiltration rate across three cropping cycles. Wheat gave three to five times more net profit than maize, and the net benefit-cost ratio of the system was the highest (1.34-1.35) when mulching was done at 60 days of maize growth with Peuraria and Leucaena. It was concluded that mulching with available vegetative materials in standing crop of maize or after harvest was beneficial for improving moisture conservation, productivity, and profitability of a maize-wheat cropping system under Doon valley conditions.
  • Authors:
    • Shipitalo, M. J.
    • Owens, L. B.
  • Source: Journal of Environmental Quality
  • Volume: 40
  • Issue: 4
  • Year: 2011
  • Summary: Residual herbicides regularly used in conjunction with conservation tillage to produce corn ( Zea mays L.) and soybean [ Glycine max (L.) Merr] are often detected in surface water at concentrations that exceed their U.S. maximum contaminant levels (MCL) and ecological standards. These risks might be reduced by planting glyphosate-tolerant varieties of these crops and totally or partially replacing the residual herbicides alachlor, atrazine, linuron, and metribuzin with glyphosate, a contact herbicide that has a short half-life and is strongly sorbed to soil. Therefore, we applied both herbicide types at typical rates and times to two chisel-plowed and two no-till watersheds in a 2-yr corn/soybean rotation and at half rates to three disked watersheds in a 3-yr corn/soybean/wheat-red clover ( Triticum aestivum L.- Trifolium pratense L.) rotation and monitored herbicide losses in surface runoff for three crop years. Average dissolved glyphosate loss for all tillage practices, as a percentage of the amount applied, was significantly less ( P≤0.05) than the losses of atrazine (21.4*), alachlor (3.5*), and linuron (8.7*) in corn-crop years. Annual, flow-weighted, concentration of atrazine was as high as 41.3 g L -1, much greater than its 3 g L -1 MCL. Likewise, annual, flow-weighted alachlor concentration (MCL=2 g L -1) was as high as 11.2 and 4.9 g L -1 in corn- and soybean-crop years, respectively. In only one runoff event during the 18 watershed-years it was applied did glyphosate concentration exceed its 700 g L -1 MCL and the highest, annual, flow-weighted concentration was 3.9 g L -1. Planting glyphosate-tolerant corn and soybean and using glyphosate in lieu of some residual herbicides should reduce the impact of the production of these crops on surface water quality.
  • Authors:
    • Sousa, D.
    • Rein, T.
  • Source: Better Crops with Plant Food
  • Volume: 95
  • Issue: 3
  • Year: 2011
  • Summary: The authors review recommended practices for evaluating and managing liming and fertilizer use for high yielding annual crops growing under no-till (NT) cultivation within the Cerrado.