• Authors:
    • Stroosnijder, L.
    • Nyakudya, I. W.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 145
  • Year: 2015
  • Summary: Food security in Sub-Saharan Africa, particularly in semi-arid tropics (41% of the region; 6 months of dry season) is threatened by droughts, dry spells and infertile soils. In Zimbabwe, 74% of smallholder farming areas are located in semi-arid areas mostly in areas with soils of low fertility and water holding capacity. The dominant crop in these areas, maize (Zea mays L.), is susceptible to drought. Under smallholder farming in Zimbabwe, conventional tillage entails cutting and turning the soil with a mouldboard plough thereby burying weeds and crop residues. Seed is planted by hand into a furrow made by the plough, ensuring that crops germinate in relatively weed free seedbeds. Inter-row weed control is performed using the plough or ox-drawn cultivators and hand hoes. Conventional tillage has been criticised for failure to alleviate negative effects of long dry spells on crops and to combat soil loss caused by water erosion estimated at 50 to 80tha-1yr-1. Therefore, conservation tillage has been explored for improving soil and water conservation and crop yields. Our objective was to determine the maize yield advantage of the introduced technology (conservation tillage) over conventional tillage (farmers' practice) based on a review of experiments in semi-arid Zimbabwe. We use a broad definition of conservation tillage instead of the common definition of =30% cover after planting. Eight tillage experiments conducted between 1984 and 2008 were evaluated. Conventional tillage included ploughing using the mouldboard plough and digging using a hand hoe. Conservation tillage included tied ridging (furrow diking), mulch ripping, clean ripping and planting pits. Field-edge methods included bench terraces (fanya juus) and infiltration pits. Results showed small yield advantages of conservation tillage methods below 500mm rainfall. For grain yields =2.5tha-1 and rainfall =500mm, 1.0m tied ridging produced 144kgha-1 and mulch ripping 344kgha-1 more than conventional tillage. Above 2.5tha-1 and for rainfall >500mm, conventional tillage had =640kgha-1 yield advantage. Planting pits had similar performance to ripping and conventional tillage but faced digging labour constraints. Experiments and modelling are required to test conservation tillage seasonal rainfall thresholds. Constraints to adoption of conservation tillage by smallholder farmers necessitate best agronomic practices under conventional tillage while work on adoption of alternative tillage methods continues.
  • Authors:
    • Munkholm, L. J.
    • Rickson, R. J.
    • Hansen, E. M.
    • Abdollahi, L.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 145
  • Year: 2015
  • Summary: Conservation tillage and diversified crop rotations have been suggested as appropriate alternative soil management systems to sustain soil quality. The purpose of this study was to quantify the effect of implementing three crop rotations (R2-R4) on soil structural changes and the "productivity function" of soil. R2 is a winter-dominated crop rotation (winter wheat was the main crop) with straw residues incorporated. R3 is a mix of winter and spring crops with straw residues removed. R4 is the same mix of crops as in R3, but with straw residues incorporated. Three tillage systems were used for each rotation: mouldboard ploughing to a depth of 20. cm (MP); harrowing to a depth of 8-10. cm (H); and direct drilling (D) at two experimental sites with a sandy loam soil and different water budgets in Denmark. The Muencheberg soil quality rating (M-SQR) method and simpler soil quality indices (i.e. visual evaluation of soil structure (VESS), overall visual structure (OVS) and overall soil structure (OSS)) were employed to differentiate the effects of these alternative management practices on soil structural quality and relative crop yield (RY). A Pearson correlation was also employed to find the correlation between the soil quality indices and relative crop yield. Relevant soil properties for calculating the soil quality indices were measured or obtained from previous publications. Crop rotation affected the soil structure and RY. The winter-dominated crop rotation (R2) resulted in the poorest soil structural quality and produced the lowest RY compared to the mixed rotations (R3 and R4). Tillage systems clearly influenced the soil quality and RY. The MP resulted in the best soil structural quality, and consequently the highest RY compared with both the reduced tillage treatments. Significant correlations were found in most cases between soil quality indices (including M-SQR) and RY. This highlights the influence of soil quality (as measured by the selected indicators) - and soil structure in particular - on crop yield potential. © 2014 Elsevier B.V.
  • Authors:
    • McCorkell, B.
    • McHenry, M.
    • Hulugalle, N.
    • Kristiansen, P.
    • Bajgai, Y.
  • Source: NUTRIENT CYCLING IN AGROECOSYSTEMS
  • Volume: 101
  • Issue: 1
  • Year: 2015
  • Summary: Despite scant crop residue input, tillage to control weeds in vegetable systems reduces soil organic carbon (SOC) levels. We hypothesized that vegetable production systems could be made more resistant to the negative effects of tillage on SOC by including a high-residue crop in rotation. Effect of sweet corn (Zea mays L. var. rugosa) residue incorporation in a corn-cabbage (Brassica oleracea L.) rotation in two soil management systems (SMS) (organic or conventional) in two soil types [a Chromosol (Alfisol) and a Vertosol (Vertisol)] on SOC and microbial biomass C (MBC) levels was tested for 2 years. Confounded factors (weed management and fertilisers) in the field experiment were separated in a multi-factorial laboratory experiment. In the field, total organic C (TOC) concentration was increased by 6.5 % in the 0-0.1 m depth by incorporating residue; however SMS exhibited inconsistent results. Organic fertilisers increased TOC whilst simulated tillage decreased it in laboratory. Soil MBC data showed that the biological fertility of soil can be improved by incorporating residues or by combining residue with organic fertiliser. In field residue incorporation in soil increased TOC, but organic fertilisers behaved inconsistently. However, in a laboratory microcosm, both residue and organic fertilisers individually mitigated tillage-induced loss of TOC.
  • Authors:
    • Freebairn, D. M.
    • Dalal, R. C.
    • Seymour, N. P.
    • Bell, M. J.
    • Moody, P. W.
    • Dang, Y. P.
    • Walker, S. R.
  • Source: Soil and Tillage Research
  • Year: 2015
  • Summary: In semi-arid sub-tropical areas, a number of studies concerning no-till (NT) farming systems have demonstrated advantages in economic, environmental and soil quality aspects over conventional tillage (CT). However, adoption of continuous NT has contributed to the build-up of herbicide resistant weed populations, increased incidence of soil- and stubble-borne diseases, and stratification of nutrients and organic carbon near the soil surface. Some farmers often resort to an occasional strategic tillage (ST) to manage these problems of NT systems. However, farmers who practice strict NT systems are concerned that even one-time tillage may undo positive soil condition benefits of NT farming systems. We reviewed the pros and cons of the use of occasional ST in NT farming systems. Impacts of occasional ST on agronomy, soil and environment are site-specific and depend on many interacting soil, climatic and management conditions. Most studies conducted in North America and Europe suggest that introducing occasional ST in continuous NT farming systems could improve productivity and profitability in the short term; however in the long-term, the impact is negligible or may be negative. The short term impacts immediately following occasional ST on soil and environment include reduced protective cover, soil loss by erosion, increased runoff, loss of C and water, and reduced microbial activity with little or no detrimental impact in the long-term. A potential negative effect immediately following ST would be reduced plant available water which may result in unreliability of crop sowing in variable seasons. The occurrence of rainfall between the ST and sowing or immediately after the sowing is necessary to replenish soil water lost from the seed zone. Timing of ST is likely to be critical and must be balanced with optimising soil water prior to seeding. The impact of occasional ST varies with the tillage implement used; for example, inversion tillage using mouldboard tillage results in greater impacts as compared to chisel or disc. Opportunities for future research on occasional ST with the most commonly used implements such as tine and/or disc in Australia's northern grains-growing region are presented in the context of agronomy, soil and the environment.
  • Authors:
    • Zhang, Q.
    • Hu, C.
    • Ren, T.
    • Du, Z.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 146
  • Issue: Pt. A
  • Year: 2015
  • Summary: Physical protection by soil aggregates is critical for building soil organic carbon (SOC) stock. The objective of this study was to identify SOC sequestrated in the microaggregate holding within macroaggregte (mM) fraction after shifting tillage systems in the North China Plain. Soil samples from 0-5. cm layer of a 6-yr field experiment (MP. -. R, moldboard plow without residue; MP. +. R, moldboard plow with residue; RT, rotary tillage with residue; NT, no-till with residue) were collected and separated into different water-stable aggregates. The macroaggregate (250-2000. µm) was further isolated into intra-aggregate particulate organic matter (iPOM) fractions by density flotation, dispersion and sieving. The results showed that the SOC concentration of fine iPOM (250f, 53-250. µm) was increased by 23% in RT and 39% in NT compared with MP. +. R, whereas the difference in the coarse iPOM (250c, >250. µm) was not observed. The ratio of 250f-250c (i.e., 250f/250c) followed the order of NT (2.12). ˜. RT (1.94). >. MP. +. R (1.50). ˜. MP. -. R (1.47), indicating the alternative tillage systems decreased the turnover rates of macroaggregates. Adoption of NT and RT improved the mM formation by 36% and 23% and mM associated C concentration by 38% and 31% as relative to MP. +. R system. Additionally, the soil C concentration and storage of the iPOM and silt plus clay fractions located within the microaggregate were higher under NT and RT than that of MP. +. R and MP. -. R systems. Thus applying NT and RT improved mM formation and soil C sequestered inside this fraction. We concluded that adoption of NT and RT enhanced SOC sequestration in the microaggregates of surface soil of the intensive agroecosystem of North China.
  • Authors:
    • Jurasinski, G.
    • Buczko, U.
    • Fiedler, S. R.
    • Glatzel, S.
  • Source: Soil and Tillage Research
  • Volume: 150
  • Year: 2015
  • Summary: Temperature-driven models of soil respiration (SR) are crucial for estimating C-balances of arable soils. However, model construction may be severely influenced by tillage operations. The impact of tillage on the temperature dependence of SR was studied to reveal the temporal patterns of model quality of temperature-driven SR-models. To obtain SR, CO2 fluxes were measured with a dynamic chamber technique in treatments of an energy crop rotation amended with biogas residues (BR) and mineral fertiliser (MF). Measurements were performed with short intervals during the first three days after tillage operations, then with extending intervals between measurements up to 35 days after tillage. Additionally, soil concentrations of hot-water extractable organic carbon (HWC) were determined before and during the experiment. Overall, in all treatments individual CO2 fluxes were affected by the extent of soil disturbance and fertiliser treatment. The highest tillage-induced fluxes where observed after disking in MF treatment. Tillage also induced an immediate increase of HWC, indicating additional labile C and a fast response of microbial activity. However, the change of HWC lasted only one day and approximated the pre-tillage values within a week. Even though BR soil had a higher HWC content, the increased C mineralisation in one repetition of MF suggests that buried plant residues might have a higher influence on SR after tillage than the type of fertiliser. Directly after soil disturbance by tillage it was impossible to construct temperature-driven models for SR in all treatments. Assuming that the coefficient of determination is appropriate with R2≥0.5 and the model quality is good with NRMSE≤0.15, the qualities of the models increased continuously with time, but were unsatisfying for at least two weeks. During this time, SR showed a high sensitivity to changing environmental influences like precipitation and soil moisture or available C for microbial turnover, rather than temperature. The treatment BR showed a less sensitive pattern, which might be attributed to an altered soil structure and microbial activity of soil after long-term application of an organic fertiliser like BR. Therefore, temperature-driven models for the prediction of soil derived CO2 emissions should be applied carefully for the days and weeks after tillage and verification by measurements in shorter intervals is advisable.
  • Authors:
    • Marquez-Garcia, F.
    • Blanco-Roldan, G. L.
    • Veroz-Gonzalez, O.
    • Gonzalez-Sanchez, E. J.
    • Carbonell-Bojollo, R.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 146
  • Issue: Pt. B
  • Year: 2015
  • Summary: The interest in conservation agriculture in Spain is evidenced by practical and institutional aspects. The practical aspect is reflected by the area cultivated under this farming system, 1.28. Mha in perennial crops and 0.57. Mha in arable crops, both for 2013. The period under review was 2009-2013 for arable crops and 2006-2013 for perennial crops. In that period, figures increased 208% for no tillage in arable crops, and 54% for groundcovers in perennial crops. The institutional support is reflected by the financial funding given to conservation agriculture farming practices by some Spanish Regional Governments, primarily through Rural Development Programs, that reached over € 200 million in the 2000-2006 period. The origins of soil conservation practices date back to the 1930s and have evolved in parallel in America and Europe. This parallelism has led to the use of different terminology for similar practices that do not always fall within the scope of conservationist practices. Consistent with the literature, and based on the results of 6 meetings with 144 Spanish experts, this paper aimed at clarifying terms and practices applied under the conditions of Spain, but could be useful for other geographies. This article also proposes definitions to clearly describe the different concepts for experts, advisers, and also for policy makers to accurately allocate funds in the European financial framework 2014-2020.
  • Authors:
    • Gutiérrez-Castorena, M. D. C.
    • Gutiérrez-Castorena, E. V.
    • Ortiz-Solorio, C. A.
  • Source: Soil and Tillage Research
  • Volume: 150
  • Year: 2015
  • Summary: In recent years, conservation tillage has been promoted as a method of increasing the quality of agricultural soils; however, in the Aridisols of northeastern Mexico, this type of tillage is not practical because of the formation of natural crusts. Conventional tillage systems that include different culture practices have been used for six decades to increase the yields. However, little is known of the changes to the soil properties and modifications to the moisture control section. Six agricultural plots representative of 78,000 ha in districts of the state of Tamaulipas, Mexico were studied based on their management: rainfed or irrigated, with or without the incorporation of crop residues and with or without plot drainage. The results show that three moisture regimes occur in the soils according to the irrigation intensity and plot drainage: aridic, ustic and udic. The aridic regime presents the greatest organic carbon stock (58Mgha-1), stability of aggregates in particles >2 mm in the arable layer and produces sorghum yields of up to 2.5tha-1. In the udic regime, because of plot drainage and the incorporation of crop residue and manure, there is high biological activity; in addition, stability of aggregates is along the whole profile, alkalinisation and redox processes occur, and short-cycle maize yields are up to 10tha-1. The different management practices for intense production modify the moisture regime but do not modify the organic carbon capture. The pedogenetic processes are related to the management intensity and cause the Aridisols to evolve into inceptisols in less than six decades of agricultural activity; however, only the redox processes are expressed in their classification despite a significant amount of calcitic features.
  • Authors:
    • Herrera, F.
    • Rasse, R.
    • Giuliante, A.
    • Donoso, L.
    • Perez, T.
    • Marquina, S.
  • Source: NUTRIENT CYCLING IN AGROECOSYSTEMS
  • Volume: 101
  • Issue: 1
  • Year: 2015
  • Summary: The largest share of Latin American and Caribbean (LAC) anthropogenic greenhouse gases is derived from land use changes as well as forestry and agriculture, representing up to 67 % of the relative contribution from all sources. However, in spite of the rapid expansion of LAC tropical agriculture, little is known about its impact on atmospheric trace gases emissions, such as nitrogen oxides (NO (x) ), nitrous oxide (N2O) and carbon dioxide (CO2), which are produced in soils by microbial processes and also accelerated in tropical climates. This information is crucial for assessing mitigation strategies linked to agricultural practices to satisfy food demands for the region's future. We measured NO, N2O and CO2 soil emissions along with soil variables from corn fields under tillage (T) and no-tillage (NT) agriculture at two of the largest cereal-producing regions in Venezuela during the crop-growing season. We found statistically significant positive correlations between the logarithms of nitrogen gas emissions and soil inorganic nitrogen concentrations, soil water and clay contents. Average emissions of NO and CO2 were larger in T than NT sites, while N2O fluxes showed the opposite. CO2 emissions from T were 1.6 as much as those found in NT, whereas N2O was 0.5 of that found in NT. These results imply that NT practices more effectively mitigate climate change from these monoculture systems mainly because of CO2 emission reduction. We suggest then that agricultural mitigation actions for tropical monoculture systems should aim for the enhancement of NT management practices along with N fertilization rate reduction to compensate for the larger N2O emissions.
  • Authors:
    • Lafond, J.
    • Paré, M. C.
    • Pageau, D.
  • Source: Soil and Tillage Research
  • Volume: 150
  • Year: 2015
  • Summary: In the northern agroecosystem of Saguenay-Lac-Saint-Jean, cash crops such as barley, canola, and field pea are gaining popularity over traditional perennial crops like alfalfa. However, very little information is available on the relatively long-term effect of different crop rotations and soil tillage practices on crop yields and soil quality parameters. This study was conducted at the Normandin Research Farm of Agriculture and Agri-Food Canada. Five rotation types [1: Canola-Barley-Barley-Pea (C-B-B-P); 2: Canola-Pea-Barley-Barley (C-P-B-B); 3: Canola-Barley-Pea-Barley (C-B-P-B); 4: Pea monoculture; and 5: Barley monoculture] and two soil tillage practices [1: Chisel plough (CP) and 2: Moldboard plough (MP)] were evaluated. Canola monoculture of was not included. The study began in 1999 on a former alfalfa field and ended in 2010 after three four-year rotation cycles. Barley monoculture decreased yields by 600kgha-1 in the last five years, whereas field pea monoculture decreased yields by about 1000kgha-1 in most years. Barley monoculture did not significantly reduce grain yields compared to C-B-B-P and C-P-B-B, highlighting the importance of alternate crops every year. Soil tillage (CP versus MP) did not significantly affect yields for all crops in most years; and when it did have an effect, it showed inconsistencies by either increasing or decreasing grain yields. Soil tillage also had insignificant impact regardless of the rotation type involved. Rotation type and soil tillage had insignificant effect on soil organic matter content, whereas CP increased nitrate and phosphorus content in the 0-20cm soil layer. Rotation type had insignificant impact on soil physical properties, whereas CP improved soil water conductivity by 0.03cmh-1 for C-B-B-P and barley monoculture. Compared to MP, CP improved soil macro-aggregate (2-6mm) stability to water as well as aggregate mean weight diameter by about 15% for most of the rotations.