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Unmanned aerial systems (UASs) are progressively being employed in an array of agricultural activities, as they come equipped with a controllable platform necessary for near real-time data acquisition. Because of these impressive advancements in geospatial technologies, the collection of important data to achieve various agricultural applications, such as crop discrimination, is increasingly being done. While they prove to be cost-effective, autonomous, and flexible in agricultural applications, a key bottleneck in such research is the lack of relevant information relating to UAV types and sensor characteristics, as well as data processing and analytical methods that are applicable for crop discrimination. As such, the study conducted a systematic review of trends, technical challenges, and opportunities. The study used PRISMA Guidelines to select, assess, and systematically review 83 articles from Web of Science, Scopus, Google Scholar, and PubMed. The findings of this review showed that rotary-wing UASs equipped with multispectral and RGB cameras were the most frequently used for crop classification. 90% of the reviewed articles noted that the deployment of these advanced technologies was predominantly in monoculture systems normally found in developed countries. Unfortunately, the potential of UASs for crop mapping and monitoring on heterogeneous smallholder farms normally practice mixed cropping systems is progressing slowly, because of technical challenges, operational costs, differing cropping systems, complex classification algorithms, environmental factors, and restrictive policies and regulations, especially in developing countries. Subsequently, research should prioritise developing simple algorithms that can accurately extract crop statistics from high-spatial resolution RGB imagery collected by UAS platforms. [ABSTRACT FROM AUTHOR]

Protracted political conflicts disrupt people's lives, including their ability to feed themselves. Urban planning, operating within the ambit of the state, impacts food systems in conflict cities. We examine the confluence of planning and political misgovernance on food sovereignty in conflict cities. We do so by documenting the experiences of urban growers who cultivate, eat, and distribute indigenous greens (haakh) in the city of Srinagar in the Himalayan belt of Jammu and Kashmir, the site of a protracted conflict. Experiences of growers were analyzed within the context of the city's complex urban planning landscape. Empirical methods included qualitative interviews of urban growers (n = 40) and review of land use plans and policies. We found that haakh production ensured access to affordable, nutritious, and culturally celebrated greens for haakh growing households. That said, intersecting burdens from undemocratic governance and militarism (from India), weak forms of local planning (within Srinagar), and climate change threaten urban growers' work, and imperils food sovereignty. Completing a study in a conflict region was extraordinarily challenging. The study's generalizability is limited by its short duration and small sample size—the inductive findings set the stage for future research. Conflict cities are a reminder that urban planning is anything but technical. Planning curricula must prepare future planners for the politics of planning. Planners in conflict cities are in liminal positions—between the state and the public. To the best of their ability, planners in conflict cities such as Srinagar have to protect smallholder growers' control of their food system, especially over land and water. The monitoring, recording, and suspension of contested or undemocratic land conversions, land grabs, or land transfers without full consent of indigenous and local peoples ought to be a local and international policy priority. [ABSTRACT FROM AUTHOR]

Few land-allocation models consider the impact of off-farm income on tropical deforestation. We provide a concept to integrate off-farm income in a mechanistic multiple-objective land-allocation model, while distinguishing between farms with and without re-allocation of on-farm labor to obtain off-farm income. On farms with re-allocation of labor we found that off-farm income reduced farmers' financial dependency on deforestation-related agricultural income leading to less tropical deforestation. The influence of off-farm income covered two aspects: availability of additional income and re-allocation of on-farm labor to off-farm activities. The labor effect tended to reduce deforestation slightly more than the income effect. On farms without re-allocation of on-farm labor we showed how farmers can use off-farm income to purchase additional labor to accelerate deforestation. Our study highlights the importance of considering off-farm income in land-use models to better understand, model and possibly curb tropical deforestation. [ABSTRACT FROM AUTHOR]

Agroecology is an approach that seeks to improve the integration of food systems through environmentally sustainable production systems. This paper explores the key practices considered to define agroecological farming in Bikita District of Masvingo in Zimbabwe. It reviewed the literature on agroecology and presented a criterion that informed analysis to distinguish between agroecological and non-agroecological farmers. Agroecological farmers mainly comprised resource-constrained farmers who sought to tap on their natural environment, local knowledge, and social networks to move away from conventional agricultural practices to achieve similar food and nutrition security and livelihood objectives as their non-agroecological counterparts. They differed from their non-agroecological counterparts mainly with respect to the diversity of crops grown, agronomic techniques used, and primary sources of income. Major challenges for farming households practising agroecological approaches includes lack of capacity for sustained adherence to agroecological principles (e.g., in the context of otherwise conventional systems; for all intends and purposes, existing extension messages and support mechanisms do not favor agroecological farming). These farmers, therefore, practice agroecological farming against institutions and policies that do not recognize agroecological farming. There is therefore currently 'no level playing field' for farmers and promoters of agroecological practices in Bikita as in many areas in Zimbabwe. [ABSTRACT FROM AUTHOR]

Conservation agriculture (CA) is recognized as a promising crop management strategy for sustainable agricultural intensification. The objective of this study was to evaluate CA cropping systems for rainfed maize as an alternative to the traditional tillage-based cropping systems (CT) in the context of family farms, using a multi-criteria model that represents the point of view of farmers. Farmers considered several aspects for evaluating the cropping systems, thatwere systematized in the model through five criteria (with sub-criteria): (a) costs; (b) yield; (c) labour; (d) human health and environment; and (e) production risks. CA did not differ from CT for the 'costs' criterion but was superior for the 'yield' and 'labour' criteria. In contrast, CT obtained better ratings for the criteria 'human health and environment' and 'production risks'. Considering all criteria, CA was better appraised than CT. However, a new local policy measure that subsidizes the hiring of mechanized tillage services overturns this outcome, indicating the importance of exogenous factors. Overall, the participatory processes in building the model allowed us to better understand the reasons of adoption or non-adoption of CA by small-scale farmers in the tropics. [ABSTRACT FROM AUTHOR]

Smallholder farms in developing countries are key to global food security and sustainability of agricultural systems. Suitable tools are needed to assess the utility of these systems for long-term policy interventions. We outline the development of a sustainability index for smallholder systems by amalgamating ecological frameworks and sustainable livelihood framework. We critically describe the process involved in the development of the indicator framework, selection of indicators, their measurement and assignment of weight, and aggregation to arrive at a composite index. A practical tool based on this index may prove helpful for long-term sustainability assessment in smallholder farms of developing countries. [ABSTRACT FROM AUTHOR]

The efficacy of various herbicides against weeds of maize was studied in field trials at Ibadan, Nigeria in 2003 and 2004. The formulations were atrazine (Gesaprim® 90 WDG at 3.5 kg a.i. ha-1 and Rhonazine® 80 WP at 3.0 kg a.i. ha-1), a mixture of atrazine and metolachlor (Primextra® Gold™ 660 SC at 4.0 kg a.i. ha-1 and Primextra® 500 FW at 2.5 kg a.i. ha-1), and a mixture of mesotrione, S-metolachlor and atrazine (Lumax® at five rates: 1.88-2.96 kg a.i. ha-1). Unweeded and hoe-weeded treatments were controls. Lumax® at all rates, Rhonazine® at 3.0 kg a.i. ha-1, and Primextra® at 2.5 kg a.i. ha-1 controlled sedges, Commelina benghalensis, and Pueraria phaseoloides as effectively as the weeded control (95-100%). Weed density and biomass were significantly reduced and maize yield increased by 12-22%. The highest yield was in treatments with 2.15 - 2.96 kg a.i. ha-1 of Lumax® and 3.5 kg a.i. ha-1 of Gesaprim®, and the weeded control. Lumax® is more effective for weed control at lower rates than the previously used formulations. [ABSTRACT FROM AUTHOR]