Posts Tagged ‘Conservation agriculture’

Re-examining appropriate mechanization in Eastern and Southern Africa : two-wheel tractors, conservation agriculture, and private sector involvement

Posted by gabrielamartinez on , in Journal Articles

56904Authors: Baudron, F., Sims, B., Justice, S., Kahan, D.G., Rose, R., Mkomwa, S., Kaumbutho, P., Sariah, J., Nazare, R., Moges, G., Gerard, B.

Published in: Food Security, In press

The need for sustainable intensification in Eastern and Southern Africa (ESA) is widely recognized as a requirement to achieve food security with minimum negative social and environmental consequences. In current Research & Development programs, much emphasis is placed on increasing the efficiency with which land, water and nutrients are used, whereas farm power appears to be a ‘forgotten resource’. This is a major concern when farm power in ESA countries is declining due to the collapse of most tractor hire schemes, the decline in number of draught animals and the growing shortage of human labour. A consequence of low levels of farm mechanization is high labour drudgery, which makes farming unattractive to the youth and disproportionally affects women. Undoubtedly, sustainable intensification in ESA will require an improvement in access to farm power. In this paper, we suggest this can be achieved through the use of small, multipurpose and inexpensive power sources such as two-wheel tractors (2WTs) coupled with the promotion of energy saving technologies such as conservation agriculture (CA), whilst ensuring the profitability for farmers, service providers and other private sector actors in the supply chain. We argue that appropriate mechanization in Africa, a paradigm largely abandoned three decades ago, may be re-examined through the combination of these three elements.

Distributing and showing farmer learning videos in Bangladesh

Posted by gabrielamartinez on , in Journal Articles

56881Authors: Bentley, J.W.; Van Mele, P.; Harun-Ar-Rashid; Krupnik, T.J.

Published in: The Journal of Agricultural Education and Extension, In press.


Purpose: To describe the results of showing farmer learning videos through different types of volunteers.

Design/Methodology/Approach: Semi-structured interviews with volunteers from different occupational groups in Bangladesh, and a phone survey with 227 respondents.

Findings: Each occupational group acted differently. Shop keepers, tillage service providers, agricultural input and machine dealers reached fairly small audiences. Tea stall owners had large, male audiences. Non-governmental organisations and community-based organisations, reached more women. The cable TV (dish-line) operators showed the videos on local TV, but some were reluctant to do so again. The Union Information Service Centres showed the videos and reached women viewers. Half of the official government extension agents surveyed also showed the videos publically.

Practical Implication: This video featured maize, wheat and rice seeding machinery. Because the machinery is complex and requires hands-on training, this first video aimed to expose tillage and sowing service providers and farmers to the machinery, without trying to teach them how to use it. But some farmers were so interested that they watched the video many times to learn more about the equipment. Before farmers and service providers decide to buy machinery for direct seeding, they still want to see and learn from demonstration plantings, to examine first-hand how the crop behaves when planted withthe new equipment.

Conservation agriculture and weed management in south Asia: perspective and development

Posted by gabrielamartinez on , in Journal Articles

56834Authors: Malik, R.; Kumar, V.; Yadav, A.; McDonald, A.

Published in: Indian Journal of Weed Science, 46(1): 31–35, 2014.


It was 20 years ago which marked the beginning of conservation agriculture (CA) with introduction of zerotillage (ZT) in wheat to (1) reduce cultivation cost so that farmers can afford to purchase new but expensive alternate herbicides for the control of herbicide-resistant population of Phalaris minor Retz., the most troublesome weed of wheat, and (2) reduce land preparation period for timely wheat planting. Worldwide, CA has spread mostly in the rain-fed agriculture but India witnessed its success more in irrigated rice-wheat cropping systems (RWCS) of the Indo-Gangetic Plains (IGP). High input based crop culture in the North West IGP has enabled weeds such as P. minor in wheat and Echinochloa crusgalli (L.) Beauv. in rice to dominate the weed flora. In wheat, zero tillage (ZT) is widely adopted by farmers in North West India and recently it is widely accepted by farmers in the eastern IGP also. In North West India, under ZT wheat, emergence and biomass of P. minor was reduced, but weed flora shifted toward more broad-leaf weeds such as Rumex dentatus (L.). In the Eastern IGP, perennial weeds such as Cynodon dactylon L. Pers. and Cyperus rotundus L. are also problematic weeds in some cases under ZT. In rice, the focus now is on dry direct-seeded rice (DSR) and machine transplanting of non-puddled rice (MTNPR) as an alternate option to puddled transplanted rice (PTR). Shifting from PTR to DSR results in changes in tillage, crop establishment method, water and weed management which often results in changes in weed composition and diversity. Weedy rice has emerged as a major threat for DSR in countries where DSR is widely adopted. In the eastern IGP, Physallis minima and Cyperus rotundus are also becoming major problematic weeds in DSR. Increased net profit for farmers by using this new technology was the main reason for rapid adoption of ZT. Since 2009, the Cereal Systems Initiatives for South Asia (CSISA), project funded by Gates Foundation and USAID and implemented by four consultative group on International Agricultural Research (CGIAR) (CG) Centers (CIMMYT, IRRI, IFPRI and ILRI) in collaboration with national partners, has explored options for sustainable intensification across the IGP, including CA-based crop management. This paper highlights the weed management scenario in conservation agriculture in India.

Multi-scale trade-off analysis of cereal residue use for livestock feeding vs. soil mulching in the Mid-Zambezi Valley, Zimbabwe

Posted by Carelia Juarez on , in Journal Articles

Published in Agricultural Systems, 2014

Baudron, F.; Delmotte, S.; Corbeels, M.; Herrera, J.M.; Tittonell, P.

Cereal residues represent a major resource for livestock feeding during the dry season in southern Africa. When kept on the soil surface instead of feeding them to livestock, crop residues can contribute to increasing soil fertility and maintaining crop productivity in the short- and the long-term. We explored these trade-offs for smallholder cotton–sorghum farming systems in the semi-arid Zambezi Valley, northern Zimbabwe. The analysis was done using simulation models at three scales, the plot, the farm and the territory, to simulate the effects of different sorghum residue allocations to livestock feeding vs. soil mulching, in combination with different application rates of mineral nitrogen fertilizer on crop productivity. The plot-scale simulations suggest that without N fertilization soil mulching has a positive effect on cotton yields only if small quantities of sorghum residues are used as mulch (average cotton yields of 2.24 ± 0.41 kg ha−1 with a mulch of 100 kg ha−1 vs. 1.91 ± 0.29 kg ha−1 without mulch). Greater quantities of mulch have a negative effect on cotton yield without N fertilization due to N immobilization in the soil microbial biomass. With applications of 100 kg N ha−1, quantities of mulch up to 3 t ha−1 have no negative effect on cotton yield. Results at farm-scale highlight the fundamental role of livestock as a source of traction, and the need to feed a greater proportion of sorghum residues to livestock as herd and farm sizes increase. Farmers with no livestock attained maximum crop production when 100% of their sorghum residue remained in the field, as they do not have access to cattle manure. The optimum fraction of crop residue to be retained in the fields for maximum farm crop production varied for farmers with 2 or less heads of cattle (80% retention), with 2–3 heads (60–80%), with 4 or more heads (40–60%). At the scale of the entire territory, total cotton and sorghum production increased with the density of cattle, at the expense of soil mulching with crop residues. The results of our simulations suggest that (i) the optimum level of residue retention depends on the scale at which trade-offs are analyzed; (ii) the retention of all of the crop residue as mulch appears unrealistic and undesirable in farming systems that rely on livestock for traction; and (iii) crop residue mulching could be made more attractive to farmers by paying due attention to balancing C to N ratios in the soil and by promoting small-scale mechanization to replace animal traction.

Effect of herbicide application on weed flora under conservation agriculture in Zimbabwe

Posted by Carelia Juarez on , in Journal Articles

Published in Crop Protection 66 1-7, 2014

Muoni, T.; Rusinamhodzi, L.;Rugare, J.T.; Mabasa, S.; Mangosho, E.; Mupangwa, W.; Thierfelder, C.

Increased challenges of weed control in the smallholder farming sector of southern Africa have often resulted in small yields. The objective of this study was to evaluate the effects of different weed control strategies on weed flora and composition under conservation agriculture (CA) systems in Zimbabwe. This study was conducted at three on-station trial sites namely Domboshawa Training Centre (DTC), University of Zimbabwe farm (UZ farm) and Henderson Research Station (HRS) in a maize–soybean rotation for four seasons from 2009–2010 to 2012–2013 seasons. Hand weeding was done whenever weeds were 10 cm tall or 10 cm in circumference for weeds with a stoloniferous growth habit. Weed identification was done up to the weed species level, and the Shannon–Weiner diversity and evenness index was used to determine the response of weed flora to herbicides. Results showed that there were more weeds in the early years which decreased gradually until the final season. Weed species diversity was not affected by herbicide application and the results indicated that weed species diversity was small in CA systems. Annual weed species constituted a greater proportion of species, and species richness decreased with the duration of the study. Richardia scabra L. and Galinsoga parviflora Cav. were the most common dominant weed species at all sites and in all seasons. Moreover, herbicide application had no effect on the evenness of weeds in the plots but site characteristics had a significant effect on the distribution of weed species (weed species evenness). The results presented in this study suggest that herbicide application facilitates a depletion of weed seed bank/number of weeds over time. Thus, herbicide application in CA has potential to reduce weed density, species richness and species diversity in the long term which may lead to more labour savings and larger yields.

Crop residue management and soil health: A systems analysis

Posted by Carelia Juarez on , in Journal Articles

Published in Agricultural Systems, 2014

Turmel, M.S.; Speratti, A.; Baudron, F.; Verhulst, N.Govaerts, B.

Due to the scarcity of alternative organic amendments, the retention of crop residue in fields can be considered key in promoting physical, chemical, and biological attributes of soil health in agricultural systems of developing countries. However, due to multiple other uses, small landholders in these countries are faced with trade-offs in managing crop residues. This article reviews crop residue management practices, mainly surface retention, incorporation or removal, describing their advantages and limitations in cereal-based agroecosystems in developing countries. The benefits of residue retention are regionally variable and depend on both agroclimatic and socioeconomic factors. Most studies from developing countries in Asia, Latin America, and Africa show positive effects of retaining crop residues on soil quality, soil organic matter and carbon storage, soil moisture retention, enhanced nutrient cycling, and decreased soil loss, among other environmental and soil health benefits. Variation was observed in the effect of surface retention vs. incorporation on various soil properties indicating the importance of taking into account abiotic factors such as climate, soil texture, study duration, sampling methods, and agronomic practices when assessing the impact of these practices. Negative effects of residue retention on crop performance attributed to nitrogen immobilization, waterlogging and decreased soil temperature have also been reported in some environments. Residue trade-offs in mixed crop-livestock systems in developing countries can limit the amount of residue retained. However, interventions such as intensification, partial retention, improved return of nutrients from manures, and the provision of substitutes to the current functions of livestock (e.g. mechanization, insurance) could reduce these residue trade-offs in favour of promoting long-term soil health.

Fate of atrazine in a soil under different agronomic management practices

Posted by Carelia Juarez on , in Journal Articles

Published in Journal of Environmental Science and Health, Part B: Pesticides, Food Contaminants, and Agricultural Wastes 49 (11) : 844-855, 2014

Prado, B.; Fuentes, M.; Verhulst, N.; Govaerts, B.; De Leon, F.; Zamora, O.

Agricultural management affects the movement of atrazine in soil and leaching to groundwater. The objective of this study was to determine atrazine adsorption in a soil after 20 years of atrazine application under agronomic management practices differing in tillage practice (conventional and zero tillage), residue management (with and without residue retention) and crop rotation (wheat-maize rotation and maize monoculture). Atrazine sorption was determined using batch and column experiments. In the batch experiment, the highest distribution coefficient Kd (1.1 L kg−1) at 0–10 cm soil depth was observed under zero tillage, crop rotation and residue retention (conservation agriculture). The key factor in adsorption was soil organic matter content and type. This was confirmed in the column experiment, in which the highest Kdvalues were observed in treatments with residue retention, under either zero or conventional tillage (0.81 and 0.68 L kg−1, respectively). Under zero tillage, the fact that there was no soil movement helped to increase the Kd. The increased soil organic matter content with conservation agriculture may be more important than preferential flow due to higher pore connectivity in the same system. The soil’s capacity to adsorb 2-hydroxyatrazine (HA), an important atrazine metabolite, was more important than its capacity to adsorb atrazine, and was similar under all four management practices (Kd ranged from 30 to 40 L kg−1). The HA adsorption was attributed to the type and amount of clay in the soil, which is unaffected by agronomic management. Soils under conservation agriculture had higher atrazine retention potential than soils under conventional tillage, the system that predominates in the study area.

Greenhouse gas emissions from nontilled, permanent raised, and conventionally tilled beds in the Central Highlands of Mexico

Posted by Carelia Juarez on , in Journal Articles

Published in Journal of Crop Improvement 28 (4) : 547-574, 2014

Dendooven, L.Patiño-Zuñiga, L.Verhulst, N.Boden, K.Garcia-Gaytan, A.Luna-Guido, M.;Govaerts, B.

Organic matter content increases in soil with no-tilled permanent raised beds (PBs) compared with soil with conventionally tilled beds (CBs), and this might affect greenhouse gas (GHG) emissions. Greenhouse gas (CO2, N2O, and CH4) emissions were measured from PBs, from which crop residue was either removed or retained and from CBs where crop residue was retained. The CO2emission was not affected by tillage, but CH4 and N2O emissions were lower in PBs when residue was retained than in CBs. Removing crop residue from PBs reduced CO2 emissions compared with when it was retained, but it had no effect on N2O and CH4 emissions. The global warming potential (GWP) of GHG emissions was higher in CBs (801 kg CO2/ha/year) than in PBs (517 kg CO2/ha/year) with crop-residue retention, but more C was sequestered in the 0–60 cm soil layer in PBs (83.4 Mg C/ha) than in CBs (79.2 Mg C/ha). Crop-residue removal in PBs had little effect on the GWP of GHG compared with PBs with crop residue retained, but less C was sequestered in the latter (63.1 Mg C/ha). Net GWP (considering soil C sequestration, GHG emissions, fuel used, glyphosate application, fertilizer and seed production) was lower in CBs with crop-residue retention (1062 kg CO2/ha/year) than in PBs with crop-residue removal (6,120 kg CO2/ha/year), but it was larger than in PBs with crop-residue retention (−681 kg CO2/ha/year). We found that reduced tillage when beds were made permanent and crop-residue retention greatly reduced net GWP compared with when beds were tilled and remade each year.We found that retention of crop residue in PBs increased the emission of CO2 compared with where it was removed, but tillage did not affect fluxes of CO2. Emission of CH4 and N2O was larger from CBs than from PBs, but crop-residue management in PBs had no significant effect on fluxes of CH4 and N2O. Concentrations of mineral N were larger in CBs than in PBs, whereas the removal of crop residue from PBs increased mineral N concentration. Soil temperature was higher in CBs than in PBs and in PBs with crop residue retained compared with where it was removed. Soil water was better preserved in PBs than in CBs and in PBs where residue was retained than where it was removed. The higher water content in the PB compared with the CB will favor plant growth during dry spells. However, retaining crop residues in PBs will require sufficient application of inorganic N, as mineral N in soil is lower in PBs than in CBs or PBs with crop residue removed. Limited N availability in PBs with crop residue retained might reduce yields as poor farmers in the central highlands of Mexico apply little or no N fertilizer. Reduced tillage on PBs and crop-residue retention strongly reduced the net GWP of the system compared with the case when beds were remade each year. PBs with residue retention reduced net GWP by 50% compared with CBs with residue retention, but the removal of residues from the PBs more than doubled it.

DSSAT modelling of conservation agriculture maize response to climate change in Malawi

Posted by Carelia Juarez on , in Journal Articles

Published in Soil and Tillage Research 143 : 85-94, 2014

Ngwira, A.R.Aune, J.B.Thierfelder, C.

Adoption of conservation agriculture (CA) is increasingly being promoted as a way of adapting agricultural systems to increasing climate variability, especially for areas such as southern Africa where rainfall is projected to decrease. The DSSAT crop simulation models can be a valuable tool in evaluating the effects of CA which are viable both economically and environmentally. Our objectives were: (1) to evaluate the ability of DSSAT to predict continuous maize (Zea mays L.) yield for conventional tillage (CT) and CA systems as well as maize yield for a CA maize–cowpea (Vigna unguiculata) rotation on an Oxic rhodustalf (2) to use DSSAT to project weather effect of climate change on yield, economic returns and risk in CT and CA systems. The DSSAT model was calibrated using data from 2007–2008 season and validated against independent data sets of yield of 2008–2009 to 2011–2012 seasons. Simulations of maize yields were conducted on projected future weather data from 2010 to 2030 that was generated by RegCM4 using the A1B scenario. The DSSAT model calibration and validation showed that it could be used for decision-making to choose specific CA practices especially for no-till and crop residue retention. Long term simulations showed that maize–cowpea rotation gave 451 kg ha−1 and 1.62 kg mm−1 rain more maize grain yield and rain water productivity, respectively compared with CT. On the other hand, CT (3131–5023 kg ha−1) showed larger variation in yield than both CA systems (3863 kg ha−1 and 4905 kg ha−1). CT and CA systems gave 50% and 10% cumulative probability of obtaining yield below the minimum acceptable limit of 4000 kg ha−1respectively suggesting that CA has lower probability of low yield than CT, thus could be preferred by risk-averse farmers in uncertain climatic conditions. Using similar reasoning, Mean-Gini Dominance analysis showed the dominancy of maize–cowpea rotation and indicated it as the most efficient management system. This study therefore suggests that CA, especially when all three principles are practiced by smallholders in the medium altitude of Lilongwe and similar areas, has the potential to adapt the maize based systems to climate change. Use of DSSAT simulation of the effects of CA was successful for no-till and crop residue retention, but poor for crop rotation. Refinement of crop rotation algorithm in DSSAT is recommended.

Improving water productivity of wheat-based cropping systems in South Asia for sustained productivity

Posted by Carelia Juarez on , in Journal Articles

Published in Advances in Agronomy 127 157-258, 2014

Kukal, S.S.;Yadvinder-SinghJat, M.L.Sidhu, H.S.

Serious water deficits are threatening agricultural sustainability in many regions of the South Asia (SA). While the increase in crop production of irrigated rice–wheat system in SA has been impressive since the 1970s, the low water productivity (WP) has led to the depletion of surface water and groundwaters. In this chapter we have discussed the availability of water resources in SA, identified the positive effects of soil and water management and crop genetic improvement on WP, and then described knowledge gaps and research priorities to further improve the WP with special emphasis on wheat-based cropping systems in irrigated and rainfed regions of SA. A single approach would not be able to tackle the forthcoming challenge of producing more food and fiber with limited or even reduced available water. Integrating irrigation water-saving techniques (water-saving irrigation methods, deficit irrigation, modernization of irrigation system, etc.) with agronomic and soil manipulations viz., optimum irrigation scheduling, direct-seeded rice, alternate wetting and drying in puddle transplanted rice, raised bed planting, crop diversification, conservation tillage, crop residue management, and conjunctive use of good quality (canal) water. Improved soil water management practices for rainfed regions include reducing runoff, rainwater harvesting and recycling, conserving rainwater in the root zone by reducing evaporation losses, and optimal nutrient management. The low WP in farmer’s fields compared with well-managed experimental sites indicates the need for more efforts to transfer water-saving technologies to the farmers. In future we need to increase scientific understanding of the effects of agronomic management on WP across various soil and climate conditions; improve irrigation practices (timing and amounts) and methods (drip and sprinkler) based on real-time monitoring of water status in soil-crop systems; and maximize WP by managing water resources and allocation at regional scales in wheat-based cropping systems.