Sustainable Weed Management for Conservation Agriculture: Options for Smallholder Farmers

Abstract

Land degradation and soil fertility deterioration are two of the main causes of agricultural production stagnation and decline in many parts of the world. The model of crop production based on mechanical soil tillage and exposed soils is typically accompanied by negative effects on the natural resource base of the farming environment, which can be so serious that they jeopardize agricultural productive potential in the future. This form of agriculture is destructive to soil health and accelerates the loss of soil by increasing its mineralization and erosion rates. Conservation agriculture, a system avoiding or minimizing soil mechanical disturbance (no-tillage) combined with soil cover and crop diversification, is considered a sustainable agro-ecological approach to resource-conserving agricultural production. A major objective of tillage is supposed to be weed control, and it does not require very specific knowledge because soil inversion controls (at least temporarily) most weeds mechanically (i.e., by way of burying them). However, repeated ploughing only changes the weed population, but does not control weeds in the long term. The same applies to the mechanical uprooting of weeds. While in the short term some tillage operations can control weeds on farms, tillage systems can increase and propagate weeds off-farm. The absence of tillage, under conservation agriculture, requires other measures of weed control. One of the ways in which this is realized is through herbicide application. However, environmental concerns, herbicide resistance and access to appropriate agro-chemicals on the part of resource-poor farmers, highlight the need for alternative weed control strategies that are effective and accessible for smallholders adopting conservation agriculture. Farmers in semi-arid regions contend with the additional challenge of low biomass production and, often, competition with livestock enterprises, which limit the potential weed-suppressing benefits of mulch and living cover crops. This paper reviews the applicability and efficacy of various mechanical, biological and integrated weed management strategies for the effective and sustainable management of weeds in smallholder conservation agriculture systems, including the role of appropriate equipment and prerequisites for smallholders within a sustainable intensification scenario.Keywords: smallholder farming; conservation agriculture; sustainable and ecological weed management; preventive; cultural and direct control methods of weed management

Soil and management‐related factors contributing to maize yield gaps in western Kenya

“…High weed cover during early stages indicates an effect of other factors related to field management, such as delayed land preparation and past farmer weed management measures, which need to be investigated. Ongoing migration to cities is reducing the labor force in rural areas, with impacts on weed control (Sims et al, ). The high engagement of young people in other income‐generating activities at the study sites seemingly has a similar effect.…”

Impact of a conservation agriculture system on soil characteristics, rice yield, and root-parasitic nematodes in a Cambodian lowland rice field

“…C. iria, C. rotundus, Digitaria spp., E. colona, E. indica, F. miliacea, M. minuta, and P. distichum) and may have played the role of refuge plants (Yik and Birchfield 1979;Anwar et al, 2011). Despite the use of cover crops, an improvement of the weed management under DMC should be targeted (Sims et al, 2018).…”

Legume Cover Crops as One of the Elements of Strategic Weed Management and Soil Quality Improvement. A Review

“…In addition, the effectiveness of weed control is also influenced by the even distribution of residual CCs and the way they are placed in the main crop. Residues of CCs on the soil surface decompose more slowly and gradually release agrochemicals, as compared to the residues mixed with the soil [117,145]. Along with an increase in the amount of mulch there was also a decrease in the occurrence of small-seeded annual weeds [46,84].…”