Conventional Tillage Agriculture Research Articles

Comparing on‐farm and long‐term research experiments on soil carbon recovery by conservation agriculture in Southern Brazil

AbstractGlobal studies, generally, and Brazilian studies, specifically, on soil organic carbon (SOC) in experimental research plots, support conservation agriculture (CA) as a tool to partially or totally restore SOC stocks depleted by conventional tillage agriculture. In response, the Brazilian Government implemented in 2010–2030 a “Low Carbon Agriculture Plan” (ABC Plan) program centered on large‐scale CA adoption. However, the projections of SOC recovery based on long‐term research trials may not adequately portray farm level high‐yield operations. The objectives of this study were: (a) quantify and compare SOC stocks to a 1‐m depth in long‐term CA at the farm scale (>20 years) with paired native vegetation and nearest available long‐term research experiments (>30 years) in Southern Brazil; (b) explore the role of oilseed radish (Raphanus sativus L.) as a cover crop to enhance SOC accumulation. In general, farm level CA systems restored SOC at an equal or higher level than the paired research plots. For the farm level CA systems, average SOC recovery was 92% (0–0.30 m) and 97% (0–1.0 m) in the soil profile relative to native vegetation. Moreover, compared to research scale CA, farm level CA average SOC recovery was 91 and 86%, for the same soil layers. Recovery of SOC in research scale CA can be scaled up to farm level systems in Southern Brazil. The main characteristics for SOC recovery (0–1.0 m) were high inputs of plant biomass, lack of soil disturbance, and diversification with oilseed radish cover crop.

Potential for Conservation Agriculture in the Dry Marginal Zone of Central Syria: A Preliminary Assessment

This paper reports on early soil related outcomes from conservation agriculture (CA) benchmark sites located within the marginal rainfed environment of agro-ecological zone 4 (annual rainfall: 200–250 mm) in pre-conflict central Syria. The outcomes reported are specifically those that relate to beneficial soil quality and water retention attributes relative to conventional tillage-based soil management practices applied to the fodder barley–livestock system, the dominant system in the zone. On-farm operational research was established to examine the impact of a barley (Hordeum vulgare) and vetch (Vicia sativa) rotation intercropped with atriplex (Atriplex halimus) and salsola (Salsola collina), under CA and conventional tillage agriculture, on the soil quality parameters and crop productivity. Preliminary results showed that CA had a positive effect on the soil quality parameters and crop performance. The soil moisture and hydraulic conductivity were higher under CA (p < 0.05), combined with improved productivity (grain and above-ground biomass) under specific crop mixes. The results suggest that despite the marginal nature of the zone, the use of CA is a viable option for the future of farmers’ livelihoods within similar localities and agro-climates, given the benefits for soil moisture and grain and straw productivity. In addition, it is likely to positively impact those in marginal environments where both pastoralism and agro-pastoralism production systems co-exist and compete for crop biomass as a main source of livestock feed. The increase in grain and straw yields vis-à-vis improvements in biophysical parameters in the CA system relative to tillage agriculture does suggest, however, that the competition with livestock for biomass is likely to reduce over time, and farmers would be able to return increased levels of straw (as stubble and residue) as mulch, given improved biomass yields.

Towards Conservation Agriculture systems in Moldova

As the world population and food production demands rise, keeping agricultural soils and landscapes healthy and productive are of paramount importance to sustaining local and global food security and the flow of ecosystem services to society. The global population, expected to reach 9.7 billion people by 2050, will put additional pressure on the available land area and resources for agricultural production. Sustainable production intensification for food security is a major challenge to both industrialized and developing countries. The paper focuses on the results from long-term multi-factorial experiments involving tillage practices, crop rotations and fertilization to study the interactions amongst the treatments in the context of sustainable production intensification. The paper discusses the results in relation to reported performance of crops and soil quality in Conservation Agriculture systems that are based on no or minimum soil disturbance (no-till seeding and weeding), maintenance of soil mulch cover with crop biomass and cover crops, and diversified cropping s involving annuals and perennials. Conservation Agriculture also emphasizes the necessity of an agro-ecosystems approach to the management of agricultural land for sustainable production intensification, as well as to the site-specificity of agricultural production. Arguments in favor of avoiding the use of soil tillage are discussed together with agro-ecological principles for sustainable intensification of agriculture. More interdisciplinary systems research is required to support the transformation of agriculture from the conventional tillage agriculture to a more sustainable agriculture based on the principles and practices of Conservation Agriculture, along with other complementary practices of integrated crop, nutrient, water, pest, energy and farm power management.

Legacy phosphorus and no tillage agriculture in tropical oxisols of the Brazilian savanna

Crop production in the Brazilian Cerrado is limited by soil phosphorus (P) supply without large inputs of inorganic P fertilizer, which may become more costly and scarce in the future. Reducing dependency on fertilizer P requires a greater understanding of soil P supply in the highly weathered soils in this important agricultural region. We investigated the impact of no tillage (NT) and conventional tillage (CT) agriculture on accumulated (legacy) soil P and P forms in four long-term sites. Compared to the native savanna soils, tilled soils receiving regular annual P fertilizer inputs (30–50 kgP ha−1) increased all forms of inorganic and organic P, except highly recalcitrant P associated with the background lithology. However, 70–85% of the net added P was bound in moderately labile and non-labile forms associated with Fe/Al oxyhydroxides rather than in plant available forms. Under NT agriculture, organic P forms and labile and non-labile inorganic P forms were all significantly (P<0.05) increased in the surface soil, except for one site with maize residues where labile inorganic P was increased more under CT agriculture. The contribution of organic P cycling in these tropical soils increased after conversion to agriculture and was proportionally greater under NT. The results highlight the large amounts of unutilized legacy P present in Brazil's Cerrado soils that could be better exploited to reduce dependency on imports of finite phosphate rock. No tillage agriculture confers a positive albeit relatively small benefit for soil P availability and overall soil function.

Dynamic emergy accounting of water and carbon ecosystem services: A model to simulate the impacts of land-use change

Expansion of agriculture over ecosystem areas is widely recognized as one of the most significant human alterations to the global environment over the last century. Although food and fiber production are essential ecosystem services (ES) to humankind, the clearing of forests for agricultural use is associated with changes in land cover which affect a wide range of ES at local, regional and global scales. Considering the importance of climate change, freshwater scarcity, soil erosion and other environmental issues, this paper aims to simulate the impact of land-use change on the ecosystem services related to water and carbon biogeochemical processes. The system under study is the Taquarizinho river basin, located in the eastern region of Mato Grosso do Sul State, Brazil, inserted in the upland borders of one of the largest wetland systems of the world, the Pantanal. Formerly occupied by Brazilian savannah (Cerrado), more than half of Taquarizinho watershed was converted both to agriculture and pasture lands since the 1960s. In order to quantify the impact of land-use change on ES provided by Taquarizinho over the years, this paper introduces the hydro-carbon model, which dynamically represents ecosystem services related to water and carbon cycles, such as canal discharge, groundwater recharge, evapotranspiration, biomass carbon sequestration, litter carbon sequestration, and soil carbon sequestration. The hydro-carbon model uses emergy for estimating the monetary value of ecosystem services provided by the river basin under different land-use scenarios. In this paper, extreme scenarios represent typical land-use types in Taquarizinho basin: native savanna (NS), agroforestry systems (AF), conventional tillage agriculture (CT), no-tillage multiple cropping agriculture (NT), degraded pastures (DP), and pastures under improved management (IP). Results in this paper reveal a hierarchy related to water and carbon ES provision, in descending order: native savanna (247EM$ha−1y−1), agroforestry system (204EM$ha−1y−1), pastures under improved management (180EM$ha−1y−1), no-tillage multiple cropping agriculture (160EM$ha−1y−1), degraded pastures (104EM$ha−1y−1) and conventional tillage agriculture (75EM$ha−1y−1).

Weeds occurrence in areas submitted to distinct winter crops

In the Western Region of Brazil, it is usual to have two agricultural harvests in the same cropping season. Usually the first crop is soybean, followed by corn. In areas where corn is not planted due to a delayed harvest of soybean, farmers generally do not use winter crops. For these areas, the planting of winter oilseed crops aiming at the production of bio-fuels is one of the best alternatives; in addition, this would help in reducing the occurrence of weed species at the following summer crop. This study aimed to assessing the weed community in distinct winter crops post soybean crop, in terms of species composition, level of infestation and severity of occurrence. The following treatments were evaluated: agriculture under a no-till system with winter fallow, winter oilseed crops (crambe, radish, rapeseed) with no-till agriculture in the summer, and agriculture under a conventional tillage system with winter fallow. Phytosociological evaluations of all treatments were carried out 75 DAE of the oilseed crops, and the diversity indexes of Margalef, Menhinick, Simpson, and Shannon-Weiner were determined. Areas were also grouped by cluster analysis based on UPGMA applied at Jaccard's similarity matrix. Among the treatments with winter coverage, radish was the most efficient crop in suppressing the occurrence of weed species. The area with conventional tillage agriculture and winter fallow allowed for a higher occurrence of troublesome weeds. On the other hand, the area under fallow showed the highest absolute level of infestation. Overall, oilseed crops in the winter contribute to lower levels of infestation by weed species in these areas.

The impacts of acid deposition on soil biota and C cycling

The paper considers process-oriented aspects of soil biotic interactions and their effects on the soil C cycle. Major emphasis is placed on results from experimental manipulations of acidity in grasslands and forests and on developing knowledge in zero-till vs. conventional tillage agriculture. In terms of both C and energy flow, a majority of the action follows the primary production detritus/decomposer pathway. Certain litter-dwelling organisms and attendant processes, such as litter decomposition, are seriously impacted by decreasing pH. Examples from forest and grassland studies are cited. Minimum tillage studies are examined next, in terms of effects of placement of residues on both biotic and abiotic responses in agricultural systems. Some little studied (as yet) groups, such as protozoa, are noted as probably important target organisms in localized pH changes at or near the soil surface. General aspects of energy and nutrient flows in ecosystems are then considered. Further studies in both theoretical and applied ecology are required to answer important questions of stress or effects, such as acid deposition in agro-ecosystems.