• Authors:
    • Aarndt, S. K.
    • Eckard, R.
    • Livesley, S. J.
  • Source: Plant and Soil
  • Volume: 309
  • Issue: 1-2
  • Year: 2008
  • Authors:
    • Dalal, R. C.
    • Salter, B.
    • Reeves, S. H.
    • Moody, P. W.
    • Wang, W. J.
  • Source: Proceedings of Australian Society of Sugarcane Technologists
  • Volume: 30
  • Year: 2008
  • Authors:
    • Place, F.
    • Ajayi, O. C.
    • Akinnifesi, F. K.
    • Sileshi, G.
  • Source: Plant and Soil
  • Volume: 307
  • Issue: 1-2
  • Year: 2008
  • Summary: A number of studies have tested the effect of woody and herbaceous legumes on soil fertility and maize yields in sub-Saharan Africa. However, their effects on maize productivity are much debated because results have been variable. A meta-analysis was conducted with the aim of evaluating the evidence in support of yield benefits from woody and herbaceous green manure legumes. A total of 94 peer-reviewed publications from West, East and southern Africa qualified for inclusion in the analysis. Maize yield from herbaceous green manure legumes (54 publications), non-coppicing legumes (48 publications), coppicing woody legumes (10 publications), natural fallows (29 publications), and fully fertilized monoculture maize (52 publications) were compared. Mixed linear modelling using yield differences (D) and response ratios (RR) indicated that the response to legumes is positive. The mean yield increase (D) over unfertilized maize was highest (2.3 t ha-1) and least variable (CV=70%) in fully fertilized maize, while it was lowest (0.3 t ha-1) and most variable (CV=229%) in natural fallows. The increase in yield over unfertilized maize was 1.6 t ha-1 with coppicing woody legumes, 1.3 t ha-1 with non-coppicing woody legumes and 0.8 t ha-1 with herbaceous green manure legumes. Doubling and tripling of yields relative to the control (RR > 2) was recorded in coppicing species (67% of the cases), non-coppicing legumes (45% of the cases), herbaceous green manure legumes (16% of the cases) and natural fallows (19% of the cases). However, doubling or tripling of yields occurred only in low and medium potential sites. Amending post-fallow plots with 50% of the recommended fertilizer dose further increased yields by over 25% indicating that legume rotations may play an important role in reducing fertilizer requirements. Except with the natural fallow, the 95% confidence intervals of D and RR were higher than 1 and 0, respectively indicating significant and positive response to treatments. Therefore, it is concluded that the global maize yield response to legumes is significantly positive and higher than unfertilized maize and natural vegetation fallows.
  • Authors:
    • Krull, E.
    • Woodbury, P.
    • Coleman, K.
    • Falloon, P.
    • Barson, M.
    • Carter, J.
    • Sohi, S.
    • Skjemstad, J.
    • Lehmann, J.
  • Source: Nature Geoscience
  • Volume: 1
  • Issue: 12
  • Year: 2008
  • Summary: Annual emissions of carbon dioxide from soil organic carbon are an order of magnitude greater than all anthropogenic carbon dioxide emissions taken together. Global warming is likely to increase the decomposition of soil organic carbon, and thus the release of carbon dioxide from soils, creating a positive feedback. Current models of global climate change that recognize this soil carbon feedback are inaccurate if a larger fraction of soil organic carbon than postulated has a very slow decomposition rate. Here we show that by including realistic stocks of black carbon in prediction models, carbon dioxide emissions are reduced by 18.3 and 24.4% in two Australian savannah regions in response to a warming of 3 degrees C over 100 years(1). This reduction in temperature sensitivity, and thus the magnitude of the positive feedback, results from the long mean residence time of black carbon, which we estimate to be approximately 1,300 and 2,600 years, respectively. The inclusion of black carbon in climate models is likely to require spatially explicit information about its distribution, given that the black carbon content of soils ranged from 0 to 82% of soil organic carbon in a continental-scale analysis of Australia. We conclude that accurate information about the distribution of black carbon in soils is important for projections of future climate change.
  • Authors:
    • Chikte, P.
    • Bhalkare, S. K.
    • Thakare, S. M.
    • Lande, G. K.
  • Source: Journal Of Cotton Research And Development
  • Volume: 22
  • Issue: 2
  • Year: 2008
  • Summary: The experiment was conducted during the kharif season of 2004-05 at Dr. PDKV, Akola to evaluate the effect of different possible intercrops on bollworm complex on cotton crop. The intercrops viz., cotton+greengram, cotton+blackgram, cotton+cowpea, cotton+sorghum, cotton+maize, cotton+marigold, cotton+soybean in 1:1 ratio alongwith a treatment of sole cotton crop were sown. The intercrop cotton+cowpea proved to be the best recording least population of spotted bollworm, American bollworm and pink bollworm as against the treatment of sole cotton crop. The highest seed cotton yield of 251 kg/ha was recorded in cotton+cowpea-intercropping system as against 160 kg/ha recorded in the sole cotton crop.
  • Authors:
    • Alves, M. C.
    • Arf, O.
    • Silva, M. G. da
    • Buzetti, S.
  • Source: Bragantia
  • Volume: 67
  • Issue: 2
  • Year: 2008
  • Summary: The soil physical properties are influenced by different soil tillage as well as by crop rotation. Field studies were conducted in Selviria, Mato Grosso do Sul, Brazil, in 2003/04, to evaluate the shoot dry matter production, soil covering percentage and the influence of crop rotation and tillage system on soil physical properties of a Rhodic Hapludox and to evaluate irrigated winter common bean yield. The treatments consisted of soil tillage systems (heavy harrow, chisel plough and no-tillage) and 6 rotations sown in the summer (maize, maize + black velvet bean, maize + brachiaria grass, soyabean, rice and sunn hemp). The crop rotations that presented larger soil coverage and shoot dry matter production were sunn hemp, maize + black velvet bean, maize + braquiaria grass and maize. No-tillage resulted in larger values of penetration resistance at 0.00-0.10 m layer. Except for macroporosity at the 0-0,1 m layer, the properties humidity, macroporosity, microporosity and total porosity of soil were not influenced by soil tillage systems. Despite differences in some yield components of common bean due to certain soil tillage or crop succession, the irrigated winter common bean crop yield was not affected.
  • Authors:
    • Koch, B.
    • Siwe, R. N.
  • Source: Environmental monitoring and assessment
  • Volume: 145
  • Issue: 1-3
  • Year: 2008
  • Summary: The continuous extraction of wood and the conversion of forest to small- and large-scale agricultural parcels is rapidly changing the land cover of the mount Cameroon region. The changes occur at varying spatial scales most often not more than 2ha for the small-scale subsistence farms and above 10ha for the extensive agricultural plantations of cocoa and palm. Given the importance of land use and land cover data in conservation planning, accurate and efficient techniques to provide up-to-date change information are required. A number of techniques for realising the detection of land cover dynamics using remotely sensed imagery have been formulated, tested and assessed with the results varying with respect to the change scenario under investigation, the information required and the imagery applied. In this study the Change Vector Analysis (CVA) technique was implemented on multitemporal multispectral Landsat data from the Thematic Mapper (TM) and Enhanced Thematic Mapper (ETM) sensors to monitor the dynamics of forest change in the mount Cameroon region. CVA was applied to multi-temporal data to compare the differences in the time-trajectory of the tasseled cap greenness and brightness for two successive time periods - 1987 and 2002. The tasseled cap was selected as biophysical indicator because it optimises the data viewing capabilities of vegetation, representing the basic types of land cover - vegetation, soil and water. Classes were created arbitrarily to predict the technique's potential in monitoring forest cover changes in the mount Cameroon region. The efficiency of the technique could not be fully assessed due to the inavailability of sufficient ground truth data. Assessment was based on the establishment of an error matrix of change versus no-change. The overall accuracy was 70%. The technique nevertheless demonstrated immense potentials in monitoring forest cover change dynamics especially when complemented with field studies.
  • Authors:
    • Suzuki, L. G. A. S.
    • Alves, M. C.
    • Suzuki, L. E. A. S.
    • Rodrigues, R. A. F.
  • Source: Científica, Jaboticabal
  • Volume: 36
  • Issue: 2
  • Year: 2008
  • Summary: The objective of this study was to verify the biomass yield potential of different cover crops in a Cerrado region, in Selviria, Mato Grosso do Sul, Brazil. The work was conducted in the Experimental University Farm of the Paulista State University (UNESP). The experimental design was the randomized complete blocks in strips with splitsplit plot: the plots were the cover crops Mucuna aterrima, Pennisetum americanum, Crotalaria juncea, Cajanus cajan and a fallow area; the split plots were the no-tillage and the conventional tillage, and the splitsplit plots were corn ( Zea mays L.), soybean ( Glycine max (L.) Merrill), and cotton ( Gossypium hirsutum L.) crops. In the winter irrigated Phaseolus vulgaris L. was the crop. In the spring/summer season the cover crop with the greatest biomass yield was Pennisetum americanum. Crotalaria juncea and the fallow area showed medium results while Mucuna aterrima and Cajanus cajan were those with the least yields. Pennisetum americanum was the crop cover with the biggest production potential of dry biomass. The cultivation systems did not influence the dry biomass of the cover crops. Only Pennisetum americanum production was influenced by crop sequence.
  • Authors:
    • Rodrigues, E.
    • Marchetti, M.
    • Goncalves, M.
    • Souza, L.
    • Ontocelli, R.
    • Lourente, E.
  • Source: Acta Scientiarum Agronomy
  • Volume: 29
  • Issue: 1
  • Year: 2007
  • Summary: Some plants for mulching have the capacity to increase the availability of nutrients in the soil - nitrogen in particular - for crop succession, thus producing positive effects on the interaction between mineral fertilizer and green manure. As a result, there is a greater possibility to obtain higher incomes than by using each one separately. The objective of this study was to evaluate the effect of antecedent crops, levels and sources of nitrogen on yield compounds and foliar nitrogen content of maize by means of no-tillage system. These were constituted by crops preceding maize, i.e., black oat, wheat, pasture turnip, hairy vetch and one fallow treatment during winter. Subplots were established by four levels of nitrogen (0; 50; 100 and 200 kg ha -1 of N), which were applied as cover. Sub-subplots were represented by two sources of nitrogen (ammonium sulfate and urea). Results showed that antecedent crops had some influence upon yield, mass of 1000 grains and foliar nitrogen content of maize. The highest yield of maize was obtained after the winter rest, the pasture turnip and also in the absence of nitrogen fertilizer application as cover. Maximum yield of maize was also obtained when sowing was done after wheat and black oat, in nitrogen levels of 140 and 137 kg ha -1, respectively. The nitrogen sources utilized had some influence only upon the index of harvest, the number of grains per ear and the foliar nitrogen content.
  • Authors:
    • Souza, L.
    • Silva, D.
  • Source: Revista Brasileira de Milho e Sorgo
  • Volume: 6
  • Issue: 2
  • Year: 2007
  • Summary: Brazil has been producing maize in almost all regions, although the costs of production increased in the last years. New techniques which provide economy without yield loss can motivate producers, as maize is an important culture used at crop rotation system. Green manure may reduce maize production costs, maily to the incorporation of nitrogen. Data from an experiment were used for these comparisons; treatments were conducted in Mato Grosso do Sul, Brazil in three precedent maize cultures (black oat, oilseed radish and hairy vetch) and six nitrogen fertilizers levels (zero, 50, 100, 150, 200 and 250 kg/ha). Maize after black oat showed damage when N 25 kg/ha was used, while increasing levels increased yield up to 150 kg/ha, wherein the maximum yield was 1233 kg/ha. Maize after oilseed radish showed under zero rate a yield of 1500 kg/ha, but MEE occurs at N 40 kg/ha. Maize after hairy vetch showed no response to N, so MEE occurs at zero N, where yield was 2100 kg/ha. Maize antecessor cultures that release more nitrogen could provide higher yield to the system with lower use of fertilizers.