• Authors:
    • Grignani, C.
    • Zavattaro, L.
    • Bertora, C.
    • Alluvione, F.
  • Source: Soil Science Society of America Journal
  • Volume: 74
  • Issue: 2
  • Year: 2010
  • Summary: Alternative N fertilizers that stimulate low greenhouse gas emissions from soil are needed to reduce the impact of agriculture on global warming. Corn (Zea mays L.) grown in a calcareous silt loam soil in northwestern Italy was fertilized with a municipal solid waste compost and vetch (Vicia villosa Roth.) green manure. Their potential to reduce N2O and CO2 emissions was compared with that of urea (130 kg N ha-1). Gaseous fluxes were measured for 2 yr in the spring (after soil incorporation of fertilizers) and in summer. In spring, the slow mineralization of compost reduced N2O emissions (0.11% of supplied N) relative to urea (3.4% of applied N), without an increase in CO2 fluxes. Nitrous oxide (2.31% of fixed N) and CO2 emissions from rapid vetch decomposition did not differ from urea. When N2O and CO2 fluxes were combined, compost reduced by 49% the CO2 equivalent emitted following urea application. Vetch did not show such an effect. In summer, no fertilizer effect was found on N2O and CO2 emissions. Compost proved to be potentially suitable to reduce the CO2 equivalent emitted after soil incorporation while vetch did not. For a thorough evaluation, net greenhouse gas emissions assessment should be extended to the entire N life cycle. Differences between calculated N2O emission factors and the default Tier 1 value of the Intergovernmental Panel on Climate Change (1%) confirmed the need for site- and fertilizer-specific estimations.
  • Authors:
    • Urquiaga, S.
    • Alves, B. J. R.
    • Giacomini, S. J.
    • Aita, C.
    • Denardin, J. E.
    • Dos Santos, H. P.
    • Dieckow, J.
    • Mielniczuk, J.
    • Bayer, C.
    • Zanatta, J. A.
    • Conceição, P. C.
    • Jantalia, C. P.
    • Boddey, R. M.
  • Source: Global Change Biology
  • Volume: 16
  • Issue: 2
  • Year: 2010
  • Summary: Conservation agriculture can provide a low-cost competitive option to mitigate global warming with reduction or elimination of soil tillage and increase soil organic carbon (SOC). Most studies have evaluated the impact of zero till (ZT) only on surface soil layers (down to 30 cm), and few studies have been performed on the potential for C accumulation in deeper layers (0-100 cm) of tropical and subtropical soils. In order to determine whether the change from conventional tillage (CT) to ZT has induced a net gain in SOC, three long-term experiments (15-26 years) on free-draining Ferralsols in the subtropical region of South Brazil were sampled and the SOC stocks to 30 and 100 cm calculated on an equivalent soil mass basis. In rotations containing intercropped or cover-crop legumes, there were significant accumulations of SOC in ZT soils varying from 5 to 8 Mg ha-1 in comparison with CT management, equivalent to annual soil C accumulation rates of between 0.04 and 0.88 Mg ha-1. However, the potential for soil C accumulation was considerably increased (varying from 0.48 to 1.53 Mg ha-1 yr-1) when considering the soil profile down to 100 cm depth. On average the estimate of soil C accumulation to 100 cm depth was 59% greater than that for soil C accumulated to 30 cm. These findings suggest that increasing sampling depth from 30 cm (as presently recommended by the IPCC) to 100 cm, may increase substantially the estimates of potential CO2 mitigation induced by the change from CT to ZT on the free-draining Ferralsols of the tropics and subtropics. It was evident that that legumes which contributed a net input of biologically fixed N played an important role in promoting soil C accumulation in these soils under ZT, perhaps due to a slow-release of N from decaying surface residues/roots which favored maize root growth.
  • Authors:
    • Bosede, A.
  • Source: African Journal of Agricultural Research
  • Volume: 5
  • Issue: 5
  • Year: 2010
  • Summary: An assessment of fertilizer use and other integrated practices was carried out with two hundred farmers selected by stratified random sampling from twenty villages in Kano and Katsina States of Nigeria. The farming system was mixed farming (legume-cereal-livestock mixture), as a strategy both to address nutrient management as well as their livelihoods (both food and income security). The major crops comprised maize, sorghum, millet, rice, soybean, groundnut and cowpea. The average farm size was 7.4 ha and livestock comprised an average of 14 goats, 15 poultry birds, 7 sheep and 9 cattle. An average of 63 kg fertilizer was applied per ha of land relative to about 649 kg of fertilizer requirement per hectare of the crops grown, very low relative to Asia and some other African countries such as South Africa, Malawi, Benin and Ethiopia. The livestock mix provided substantial farmyard manure for fertilizing the soils and supplemented farm drought animals/animal traction while the crop residues (legumes and cereals) provided feeds for the livestock. It was found that fertilizer use multiplies the returns on farmers' output by a factor of 2.1-14.6, which was relatively higher than previous findings (IFDC, 2002) for the same crops in Nigeria, but crop yields were comparatively less for other Sub-Saharan and Asian countries. The observed higher response coefficient could be explained by the use of organic/farmyard manures and other soil conservation practices. Farmers exploit land and the natural fertility of the soil through continuous cropping and poor fertilization (organic and inorganic). Critical environmental issues emanating from these are soil nutrient depletion, soil degradation by erosion, weed and pest invasion, all culminating in sustained low productivity. It was therefore concluded that sustained growth in agricultural productivity without environmental exploitation and degradation cannot be achieved unless efforts to enhance farmers' fertilizer use and organic fertilization are taken seriously. Efforts should be put in place to correct fertilizer market inadequacies, particularly to monitor the quality standard and guarantee farmers' access to fertilizers, as well as encourage National research and extension programs to emphasize economic use of basic local materials for effective fertilization of farmers' fields, reduced vulnerability to nutrient loss and drought, and increased agricultural productivity.
  • Authors:
    • Chianu, J.
    • Kimetu, J.
    • Waswa, B.
    • Vanlauwe, B.
    • Kihara, J.
    • Bationo, A.
  • Source: Experimental Agriculture
  • Volume: 46
  • Issue: 1
  • Year: 2010
  • Summary: Many food production systems in sub-Saharan Africa are constrained by phosphorus (P).We hypothesized that within legume-cereal rotation systems: targeting P to the legume phase leads to higher system productivity, and that use of grain legumes leads to better economic returns than use of herbaceous legumes. Four P application regimes: (i) no P, (ii) P applied every season, (iii) P applied in season 1 only and (iv) P applied in season 2 only were tested for four seasons in three cropping systems (continuous maize, mucuna-maize rotation and soybean-maize rotation) in a split plot experiment set up in Nyabeda, western Kenya. Treatments where P was applied were better than no P treatments.While continuous cereal systems showed the need for application of P every second season, rotation systems involvingmucuna and soyabean indicated that application in one out of three seasons could be sufficient. Nitrogen fertilizer equivalence was 52 to >90 kg N ha -1 for soyabean and 37 to >90 kg N ha -1 for mucuna, depending on P fertilization and season. Analysis of marginal rates of return (MRR) showed that soybean-maize rotation with one application of P was the most economically viable option, with an MRR of at least 147% compared to other non-dominated options.
  • Authors:
    • Obi, M.
    • Obalum, S.
  • Source: Soil & Tillage Research
  • Volume: 108
  • Issue: 1/2
  • Year: 2010
  • Summary: Evaluation of the impact of tillage-mulch practices under different cropping systems on soil physical properties is needed in southeastern Nigeria to identify those combinations with the potential of alleviating the physical constraints of the Ultisols predominant in the area. An investigation was carried out on a sandy loam soil at Nsukka to determine the effects of no-till (NT) and conventional tillage (CT) each with bare fallow (B) and mulch cover (M) on soil physical properties under three cropping systems [sole sorghum ( Sorghum bicolor L. Moench), sole soybean ( Glycine max L. Merrill), and sorghum-soybean intercrop]. The layout was a split-plot in randomized complete block design, with the tillage systems as the main plots and the mulch practices as the sub-plots. The treatments [no-till and bare (NTB), no-till with mulch (NTM), conventional tillage and bare (CTB) and conventional tillage with mulch (CTM)] were replicated four times. The selected key parameters evaluated after two years were density of earthworm casts, soil organic matter (SOM), bulk density (BD), total porosity (TP), pore size distribution (PSD), mean weight diameter (MWD), and saturated hydraulic conductivity (K sat). Earthworm activity was significantly ( P≤0.001) higher with NT under the intercrop system. Values were generally very low for SOM (1.06-1.48%), moderate for BD (1.34-1.51 Mg m -3) and TP (46-52%), and low to moderate for MWD (1.1-2.9 mm). The K sat was within the slow to rapid range (8.1-57.0 cm h -1). Neither the tillage nor the mulch factors influenced SOM, BD, PSD, and MWD in the cropping systems. The TP was significantly ( P≤0.05) higher in the CT compared to the NT under the sole sorghum, where interaction showed higher value in the CTM compared to the rest. There was significant ( P≤0.05) enhancement of K sat in the CT under the sole sorghum and the intercrop systems; whereas the value was significantly ( P≤0.01) higher in the bare fallow under the sole soybean. The cropping systems had more pronounced effect on the physical properties than the tillage-mulch management practices. All the measured parameters indicated significant ( P≤0.05) improvements under the sole soybean, except BD and MWD which were significantly ( P≤0.05) improved under the intercrop. Intercropping cereals and legumes on NT may be ideal for alleviating the soil's structural constraints.
  • Authors:
    • Bradford, S.
    • Crohn, D.
    • Poss, J.
    • Shouse, P.
    • Segal, E.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 137
  • Issue: 3/4
  • Year: 2010
  • Summary: A nutrient management plan (NMP) field experiment was conducted to investigate the fate of nitrogen (N), phosphorus (P), potassium (K) and salts in a semi-arid environment (San Jacinto, CA). Our mechanistic approach to study NMP performance was based on comprehensive measurements of water and N mass balance in the root zone. A cereal crop rotation (wheat-rye hybrid to sorghum, Triticum aestivum L.- Secale cereale L. to Sorghum bicolor L. Moench) that does not fix atmospheric N was employed during 2007, whereas a legume crop (alfalfa, Medicago sativa L.) that forms nodules to fix N was used in 2008. Blending (2007 and 2008) and cyclic (2007) dairy wastewater (DWW) application strategies (no statistical difference in 2007) were implemented to meet crop water and N uptake. The high content of salts in DWW and accurate application of water to meet evapotranspiration ( ET) yielded salt accumulation in the root zone. Leaching these salts after the fallow period resulted in the flushing of nitrate that had accumulated in the root zone due to continuous mineralization of soil organic N. This observation suggested that a conservative NMP should account for mineralization of organic N by (i) leaching salts following harvests rather than prior to planting and (ii) maintaining soils with low values of organic N. For the wheat-rye hybrid-sorghum rotation, losses of nitrate below the root zone were minimal and the soil organic N reservoir and P were depleted over time by applying only a fraction of the plant N uptake with DWW (28-48%) and using DWW that was treated to reduce the fraction of organic N (3-10%), whereas K accumulated similar to other salts. Conversely, with alfalfa approximately 15% of the applied N was leached below the root zone and the soil organic N increased during the growing season. These observations were attributed to fixation of atmospheric N, increased root density, and applying a higher fraction of plant N uptake with DWW (76%). Collectively, our results indicate that NMPs should accurately account for water and nutrient mass balances, and salt accumulation to be protective of the environment.
  • Authors:
    • Sundermeier, A.
    • Diedrick, K. A.
    • Dygert, C. E.
    • Mullen, R. W.
    • Henry, D. C.
  • Source: Agronomy Journal
  • Volume: 102
  • Issue: 1
  • Year: 2010
  • Summary: Inclusion of a winter legume cover crop into a crop rotation has been suggested as a method to provide a substantial portion of the N requirement of the following crop. While the benefits of winter cover crops such as reduced soil erosion, increased soil organic matter, and increased mulch cover have been well documented, the N contribution to the subsequent crop has shown to be variable. The objective of this study was to determine the N contribution from a red clover (Trifolium pratense L.) cover crop following wheat (Triticum aestivum L.) to a subsequent corn (Zea mays L.) crop. The experiment was conducted at two western Ohio locations over 3 yr. At both locations, red clover was either interseeded into wheat or seeded after harvest, the red clover cover crop was eliminated with tillage or herbicide application, and corn was planted with three N rates (0, 90, and 180 kg N ha(-1)). The data revealed that for three of the four site years (when the cover crop was successfully established) there was no N contribution attributable to the presence of red clover. The one site that did show a N contribution revealed that the amount of N contributed was less than 90 kg N ha(-1). However, even when no N benefit was found, yields were improved by non-N-related rotational effects. Significant reductions in N fertilization rates following a red clover cover crop are likely to result in lost corn yield opportunities in western Ohio.
  • Authors:
    • Ginovart, M.
    • Josa, R.
    • Sole, A.
  • Source: International Agrophysics
  • Volume: 24
  • Issue: 2
  • Year: 2010
  • Summary: In an experiment conducted in NE Spain, cereals and legumes were rotated for seven cycles using two different tillage techniques - conventional tillage and direct drilling (no-tillage: NT). Straw was removed after harvesting in both tillage systems. With NT, more than 30% of the soil surface was still covered by residues (stubble) at sowing. The soil was Calcic Cambisol and the climate aridity index was 0.76. The climatic water balance was negative, at -187 mm y(-1) from 1950 to 1980. The aims of the study were to determine the effect of tillage system on 2-D macroporosity by micromorphology, and bulk density (excavation method) of the upper layer of the ploughed horizon. To identify differences, either parametric or nonparametric statistical tests were performed depending on sample size. Direct drilling with residue removal affected bulk density, macroporosity and mean macropore area in the top 10 cm of the profile. The same effects were observed under conventional tillage. The upper layer of the studied horizon had higher total porosity than the layer beneath with both treatments. The upper layer of the horizon showed unfavourable physical conditions with direct drilling.
  • Authors:
    • Jajoo, S. B.
    • Kambale, P. G.
    • Atal, G. R.
  • Source: Green Farming OR Soil & Water Conservation Engineering
  • Volume: 1
  • Issue: 1
  • Year: 2010
  • Summary: A study was conducted to suggest optimal resources allocation i.e. land and water using linear programming model for Amravati district in Maharashtra State. Considering the land capability classification, availability of water in different seasons, crop water requirements, food requirements of the district, affinity towards the crops and investment capacity of peoples, crop plan was developed to maximize the net return. In existing crop plan during kharif season major area is under cotton (32.41%) followed by soybean (20.19%) whereas in proposed optimal crop plan without capital constraints major area was allocated under soybean (30%), cotton (10%) and jowar (10%) of cultivable area. In rabi major area in existing crop plan is under gram (5.2%) whereas in proposed plan area is allocated to wheat (30%) followed by gram (27%). In existing crop plan gross investment and net return were Rs. 9,268 and Rs. 4,906 per ha where as in proposed plan Rs. 16,057 and Rs. 9,642 per ha. Thus increases net return by Rs. 4,362 by increasing gross investment of Rs. 6,415 per ha.
  • Authors:
    • Avcioglu, R.
    • Soya, H.
    • Demiroglu, G.
    • Kir, B.
  • Source: Turkish Journal of Field Crops
  • Volume: 15
  • Issue: 2
  • Year: 2010
  • Summary: This study was conducted in the experimental fields of Field Crops Department of Agriculture Faculty in Ege University, Bornova, Izmir-TURKEY under Mediterranean environmental conditions in the years, 2003-2009. Three legumes (Medicago satire, Lotus corniculatus and Trifolium resupinatum) and four grasses (Bromas inermis, Festuca erundinaceae, Dactylis glomerate and Arrhenatherum elatius) with Sanguisorha minor were sown in rows 15 cm apart and tested for some yield and quality characteristics under cattle grazing regime. Medicago satire and Festuca erundinaceae were the permanent and most successful legume and grass in the mixture in terms of botanical composition and cover traits throughout the experimental years. With respect to dry matter and crude protein yield characteristics, same components of the mixture also performed very well and have been evaluated as recommendable for all resembling Mediterranean environments. It was also suggested that Lotus corniculatus and Arrhenatherum elatius, both exhibiting stable and sustainable dry matter and crude protein yield contribution to overall performances of the sward, should be included in this type of Mediterranean pasture mixture. The general performance of this rotation pasture mixture was quite sustainable and suggested to utilize the sward economically for another couple of years.