• Authors:
    • Robertson, G. P.
    • Thelen, K. D.
    • Corbin, A. T.
    • Leep, R. H.
  • Source: Agronomy Journal
  • Volume: 102
  • Issue: 6
  • Year: 2010
  • Summary: Agronomic management during the 3-yr transition period to organic certification influences soil quality and the weed seedbank. We studied two cropping systems during the transition period and the first certified organic season. A 4-yr rotation of corn, soybean, wheat/alfalfa, corn (C-S-W/A-C) [Zea mays L., Glycine max (L.) Merr., Triticum aestivum L., Medicago sativa L.], produced under a more complex management that included manure and cover crop residue, was compared to a perennial based corn, alfalfa, alfalfa, corn (C-A-A-C) rotation. We compared soil aggregate size distribution and bulk density after Year 1 and on completion of the transition period. Weed seedbank populations were quantified through two seasons in the greenhouse. Weed surface density and aboveground weed biomass were quantified in the field. Over the course of the study, the percentage of large soil macroaggregates (> 2000 mu m size class) had 2.7 and 3.4-fold increase for the C-A-A-C and C-S-W/A-C treatments, respectively. The C-S-W/A-C system generated a 4.5-fold increase in aggregates of this class when wheat that was interseeded with alfalfa was harvested as forage. Bulk density decreased 14 and 6% for the C-S-W/A-C and the C-A-A-C systems, respectively. There was a 60 to nearly 300% increase in total weed seeds germinated in the greenhouse for the C-S-W/A-C system. This same system had a 60 to more than 500% decreased weed seedbank density in the field. We conclude from this study that either strategy can improve soil quality while the weed seedbank was better managed in the more complicated C-S-W/A-C system.
  • Authors:
    • Țărau, D.
    • Borza, I.
    • Dicu, D.
  • Source: Research Journal of Agricultural Science
  • Volume: 42
  • Issue: 3
  • Year: 2010
  • Summary: Studies were conducted on a cambic cernosiom, with a medium content of clay, dominant in the Prodagro West Arad agro-centre and representative for a large surface in the Banat-Crisana Plain, on the Arad cadasiral territory, Romania. The experimental factors considered include: soil work system; foliar phyto-sanitary treatment; classical system; and no-till system. From the geomorphological point of view, the perimeter on which the experiments are located belongs to the large physical-geographic unity called the Vinga High Plain. Relief present itself as a succession of high plain, almost even, with altitudes between 95-200 m, separated by wide valleys, rather deep, collected quite in exclusivity by Berecsau river (and less by Mires river). The zone between the rivers are well individuated in 5 steps layed in fan shape: Seceani (180 m), Alios (160 m), Vinga (150 m), Calacea (130 m), Satchinez (100 m) realized by Mires river at different geological moments an partly tectonically influenced. Hydrographically, the perimeter where the experiment is placed belongs to the hydrographic basin of Mires river which flows at approximately 2-3 km north from this. The pedophreatic levels are at 5.1-10 m depth (they do not interfere in the pedogenesis processes) in flat areas and between 1.5-3.0 m depth in the valleys. For wheat, the production was between 3613-4817 kg/ha, the highest production of 4817 kg/ha, being registered in the no-till system, treated and the lowest of 3613 kg/ha in the no-till system . For maize the obtained production had values of 3658-5680 kg/ha, the highest production of 5680 kg/ha, being registered in classic system treated and the lowest of 3658 kg/ha in no-till system untreated.
  • Authors:
    • Sabău, N. C.
    • Samuel, A.
    • Brejea, R.
    • Domuța, C.
    • Borza, I.
    • Bara, C.
    • Bara, L.
    • Vușcan, A.
    • Ciobanu, G.
    • Gîtea, M.
    • Moza, A.
    • Jurca, A.
    • Șandor, M.
    • Domuța, C.
  • Source: Research Journal of Agricultural Science
  • Volume: 42
  • Issue: 1
  • Year: 2010
  • Summary: The paper is based on the research carried out during 2007-2009 in the long term trial placed in 1990 on the preluvosoil from Agricultural Research and Development Station Oradea. The preluvosoil from the research field is characterized by the presence of the horizons Bt 1 (34-54 cm depth) and Bt 2 (54-78 cm depth); the colloid clay eluviation determined to appear the El horizon with 31.6% colloid clay. On 0-20 cm depth, the soil has a big percentage of macroaggregates (Phi >0.25 mm), 47.5% bulk density is of 1.41 g/cm 3 and total porosity is median one, hydraulic conductivity is of 21.0 mm/h. The values of the pH indicates a low acid soil, humus, total nitrogen, phosphorus and potassium content are low. The source of irrigation water was a drill of 15 m depth. The chemical parameters of the irrigation water were the following: fixed mineral residue 0.5 g/l; SAR index 0.52; CSR index=-1.7%; N. Florea class=II; there are not some problems regarding the use of irrigation use. There are two factors of the experiment: crop rotation (wheat-monocrop, maize-wheat; maize-soybean-wheat) and water regime (unirrigated; irrigated). Optimum water provisionment was assured in the irrigated variant maintaining the soil water reserve between easily available water content on 0-50 cm depth. The biggest protein and gluten content were determined in the wheat grains from maize-soybean-wheat crop rotation both in unirrigated and irrigated variant and the smallest values were registered in the wheat monocrop. In the irrigated variant the smaller values protein, wet and dry gluten were registered but the differences are unsignificant. The research results emphasized the importance of the crop rotation to obtain an wheat yield with good panification index. The research results are part in the project: PN-II-ID-PCE-2008 2; 690/2009 "The study of influences of some technological elements upon the wheat yield quality in the conditions of the North-Western part of Romania".
  • Authors:
    • Petersen, J. L.
    • Melvin, S. R.
    • Irmak, S.
    • Martin, D. L.
    • Donk, S. J. van
    • Davison, D. R.
  • Source: Transactions of the ASABE
  • Volume: 53
  • Issue: 6
  • Year: 2010
  • Summary: Competition for water is becoming more intense in many parts of the U.S., including west-central Nebraska. It is believed that reduced tillage, with more crop residue on the soil surface, conserves water, but the magnitude of water conservation is not clear. A study was initiated on the effect of residue on soil water content and corn yield at North Platte, Nebraska. The experiment was conducted in 2007 and 2008 on plots planted to field corn ( Zea mays L.). In 2005 and 2006, soybean was grown on these plots. There were two treatments: residue-covered soil and bare soil. Bare-soil plots were created in April 2007. The residue plots were left untreated. In April 2008, bare-soil plots were recreated on the same plots as in 2007. The experiment consisted of eight plots (two treatments with four replications each). Each plot was 12.2 m * 12.2 m. During the growing season, soil water content was measured several times in each of the plots at six depths, down to a depth of 1.68 m, using a neutron probe. The corn crop was sprinkler-irrigated but purposely water-stressed, so that any water conservation in the residue-covered plots might translate into higher yields. In 2007, mean corn yield was 12.4 Mg ha -1 in the residue-covered plots, which was significantly (p=0.0036) greater than the 10.8 Mg ha -1 in the bare-soil plots. Other research has shown that it takes 65 to 100 mm of irrigation water to grow this extra 1.6 Mg ha -1, which may be considered water conservation due to the residue. In 2008, the residue-covered soil held approximately 60 mm more water in the top 1.83 m compared to the bare soil toward the end of the growing season. In addition, mean corn yield was 11.7 Mg ha -1 in the residue-covered plots, which was significantly (p=0.0165) greater than the 10.6 Mg ha -1 in the bare-soil plots. It would take 30 to 65 mm of irrigation water to produce this additional 1.1 Mg ha -1 of grain yield. Thus, the total amount of water conservation due to the residue was 90 to 125 mm in 2008. Water conservation of such a magnitude will help irrigators to reduce pumping cost. With deficit irrigation, water saved by evaporation is used for transpiration and greater yield, which may have even greater economic benefits. In addition, with these kinds of water conservation, more water would be available for competing needs.
  • Authors:
    • Hu, C. S.
    • Ren, T. S.
    • Du, Z. L.
  • Source: Soil Science Society of America Journal
  • Volume: 74
  • Issue: 1
  • Year: 2010
  • Summary: Little information is available about their influences of conservation tillage on the distribution and storage of soil organic C (SOC) and total N in soil profiles in the North China Plain. We investigated the changes in SOC and total N as related to the shift from conventional to conservation tillage using a long-term field experiment with a winter wheat ( Triticum aestivum L.)-corn ( Zea mays L.) double cropping system. The experiment included four tillage treatments for winter wheat: moldboard plow without corn residue return (MP-R), moldboard plow with corn residue return (MP+R), rotary tillage (RT), and no-till (NT). Compared with the MP-R treatment, returning crop residue to the soil (MP+R, RT, and NT) increased SOC and total N in the 0- to 30-cm soil layer, but no distinct changes in SOC and total N concentration were observed among the four treatments at soil depths >30 cm. Compared with the MP+R treatment, the RT and NT treatments increased SOC and total N concentration significantly in the 0- to 10-cm layer but decreased SOC and total N concentration in the 10- to 20-cm layers. As a consequence, soil profile SOC and total N storage did not vary among the MP+R, RT, and NT treatments. Thus under the experimental conditions, conservation tillage (RT and NT) increased SOC and total N contents in the upper soil layers, but did not increase SOC and total N storage over conventional tillage (MP+R) in the soil profile.
  • Authors:
    • Bayer, C.
    • Vieira, R. C. B.
    • Fontoura, S. M. V.
    • Ernani, P. R.
    • Moraes, R. P. de
  • Source: Revista Brasileira de Ciência do Solo
  • Volume: 34
  • Issue: 6
  • Year: 2010
  • Summary: Little is known about the agronomic effectiveness of phosphate rocks in high-yielding crop rotation systems under no-till in the Center-South of the state of Parana, Brazil. This field study was undertaken to compare the effectiveness of rock phosphates and soluble P fertilizers to increase the yield of several annual crops grown in two consecutive triennial crop-rotation cycles under no-tillage. The experiment was carried out in an Oxisol, in Guarapuava, PR, from 2000 until 2006. Two phosphate rocks (PR - Gafsa and Arad) and a soluble P fertilizer (TSP - triple superphosphate) were broadcast over the soil surface at rates of 0, 40, 80 and 160 kg ha -1 P 2O 5, at the beginning of the first and the second rotation cycle of the triennial crops (oat, maize, wheat, soybean, barley and soybean). With exception of barley, crop yields were not affected in the first rotation cycle by any phosphate fertilizer regardless of type and rate, probably due to the high P contents available in the soil (8.7 mg dm -3 in the 0-10 cm layer). In the second rotation cycle, when soil available P was 4.1 mg dm -3; P application at oat sowing increased the yield of summer crops by 11% and of winter crops by 20%. The yield increment was lowest for maize (8%) and highest for barley (44%). In this cycle, TSP resulted in higher yield than PR, though only for winter crops (oat, wheat and barley), in a mean of 11%, with no difference between Gafsa and Arad. Water soluble fertilizer (TSP) was more efficient than phosphate rocks in soils under no-till system both in the short and long term. Nevertheless, it is not necessary to apply phosphates for high yields in soils with high available P contents under no-till, except for species with high P requirement, e.g., barley.
  • Authors:
    • Dercon, G.
    • Nziguheba, G.
    • Iwuafor, E. N. O.
    • Berkhout, E. D.
    • Franke, A. C.
    • Vandeplas ,I.
    • Diels, J.
  • Source: Experimental Agriculture
  • Volume: 46
  • Issue: 4
  • Year: 2010
  • Summary: Integrated crop-livestock farming in the Guinea savanna of West Africa is often assumed to lead to synergies between crop and livestock production, thereby improving the overall productivity and resilience of agricultural production. Whether these synergies actually occur remains poorly studied. On-farm trials were conducted in northern Nigeria over a period of four years to assess the agronomic and economic performance of maize-legume systems with and without the integration of livestock (goats). Groundnut-maize rotations with livestock achieved the highest carry-over of nutrients as manure from one season to the next, covering approximately one-third of the expected N, P and K uptake by maize and reducing the demand for synthetic fertilizers. However, the advantage of lower fertilizer costs in rotations with livestock was offset by higher labour costs for manure application and slightly lower values of maize grain. Overall, no clear agronomic or economic benefits for crop production were observed from the combined application of manure and synthetic fertilizer over the application of synthetic fertilizer only, probably because the amounts of manure applied were relatively small. Legume-maize rotations achieved higher cereal yields, a better response to labour and fertilizer inputs, and a higher profitability than maize-based systems with no or only a small legume component, irrespective of the presence of livestock. Livestock at or near the farm could nevertheless make legume cultivation economically more attractive by increasing the value of legume haulms. The results suggested that factors other than crop benefits, e.g. livestock providing tangible and non-tangible benefits and opportunities for animal traction, could be important drivers for the ongoing integration of crop and livestock production in the savanna.
  • Authors:
    • Kuhn, A.
    • Hiepe, C.
    • Judex, M.
    • Gaiser, T.
  • Source: Agricultural Systems
  • Volume: 103
  • Issue: 9
  • Year: 2010
  • Summary: Upscaling of crop models from the field scale to the national or global scale is being used as a widespread method to make large-scale assessments of global change impacts on crop yields and agricultural production. In spite of the fact that soil fertility restoration and crop performance in many developing countries with low-input agriculture rely strongly on fallow duration and management, there are only few approaches which take into account the effect of fallowing on crop yields at the regional scale. The objectives of this study were to evaluate the sensitivity of maize yield simulations with the Environmental Policy Integrated Climate (EPIC) model to fallow availability at the field and regional scale and (2) to present a novel approach to derive a model-based estimate of the average fallow availability within a typical catchment of the sub-humid savanna zone of West Africa. Therefore, the EPIC model has been validated at the field scale and then incorporated into a spatial database covering a typical catchment within the sub-humid savanna zone of West Africa with 121 sub-basins. Maize-fallow rotations have been simulated within 2556 quasi-homogenous spatial units and then aggregated to the 10 districts within the catchment assuming three different scenarios of fallow availability: 100% of the bush-grass savanna area is available and used in fallow-crop rotations (FU100), 50% of the bush-grass savanna area is available and used in fallow-crop rotations (FU50) and 25% of the bush-grass savanna area is available and used in fallow-crop rotations (FU25). A new aggregation procedure has been developed which is based on changes in the frequency of fallow-cropland classes within the sub-basins to render the simulation results in the spatial database sensitive to changes in fallow availability. Comparison of the average simulated grain yield with the mean yield over the catchment shows that the simulations overestimate maize yields by 62%, 44% and 15% for scenario FU100, FU50 and FU25, respectively. The best agreement between simulated and observed crop yields at the district scale was found when using the assumption that 25% of the savanna is available as fallow land under the present cropping patterns, which corresponds to a fallow-cropland ratio of 0.9. Comparison with farm surveys shows that the combination of remote sensing and dynamic crop modelling with yield observations provides realistic estimates of effective fallow use at the regional scale. (C) 2010 Elsevier Ltd. All rights reserved.
  • Authors:
    • Zhang, J. P.
    • Sun, J. S.
    • Liu, Z. G.
    • Qiu, X. Q.
    • Duan, A. W.
    • Gao, Y.
    • Wang, H. Z.
  • Source: Agricultural Water Management
  • Volume: 98
  • Issue: 1
  • Year: 2010
  • Summary: In a field experiment in the Yellow River Basin conducted in 2007 and 2008, it was found that, under full irrigation, the roots of maize not only penetrated deeper than those of soybean but also extended into soybean stands underneath the space between inner rows of soybean. The roots of soybean, however, were confined mainly to the zone near the plants. Horizontal growth of the roots of both the crops was confined mainly to the soil layer 16-22 cm below the surface, a layer that lay above an existing plough pan. Root length density (RLD) was much higher in the top layer (0-30 cm deep) and in the zone closer to the plants. The exponential model proved suitable to describe the RLD vertically and horizontally in both sole cropping and in intercropping.
  • Authors:
    • Wang, H. Z.
    • Chen, J. P.
    • Zhang, J. P.
    • Qiu, X. Q.
    • Duan, A. W.
    • Gao, Y.
  • Source: Chinese Journal of Eco-Agriculture
  • Volume: 18
  • Issue: 5
  • Year: 2010
  • Summary: In this study, a radiation interception and utilization model was developed through an experiment on maize/soybean intercropping systems with different intercropping proportions of maize and soybean to assess crop growth and yield. In the model, crop biomass and yield are calculated as functions of photosynthetic active radiation ( PAR), radiation interception fraction ( F) and radiation use efficiency ( RUE). PAR is estimated from ratios of PAR to solar radiation (). F is calculated by using the Keating and Carberry equation. Time for emergence, flowering and maturity are determined by growing degree days ( GDD) since planting. Results indicate that the model accurately simulates total biomass and yield of fully irrigated maize/soybean intercropping system.