Remote Sensing Applications in Tobacco Yield Estimation and the Recommended Research in Zimbabwe

Abstract

Tobacco crop area and yield forecasts are important in stabilizing tobacco prices at the auction floors. Tobacco yield estimation in Zimbabwe is currently based on statistical surveys and ground-based field reports. These methods are costly, time consuming, and are prone to large errors. Remote sensing can provide timely information on crop spectral characteristics which can be used to estimate crop yields. Remote sensing application on agriculture in Zimbabwe is still very limited. Research should focus on identifying suitable reflectance indices that are related to tobacco growth and yield. Varietal yield response to fertiliser and planting dates as well as suitable temporal windows for spectral data collection should be identified. The challenges of the different tobacco land sizes have to be overcome by identifying suitable satellite platform, with sufficient spectral resolution to separate the tobacco crop from the adjacent competing crops and noncrop vegetative surfaces. The identified suitable index should be strongly correlated with tobacco in season dry mass and yield. The suitable vegetative indices can be employed in establishing tobacco cropped area and then apply the long-term area yield relationship from government and nongovernmental statistical departments to estimate yield from remote sensing derived cropped area. BackgroundZimbabwe is the largest producer of tobacco in Africa and the world's fourth-largest producer of flue-cured tobacco (Nicotiana tabacum), after China, Brazil, and the United States of America. Tobacco production has been the leading driver behind the 34% growth in Zimbabwe's agriculture and one of the major sources of foreign currency [1]. Tobacco crop plays an important role in the economy of Zimbabwe and in the 2012/2013 marketing season, 144 million kg of tobacco was sold, earning the country $525 million [2].Crop area and yield forecasts play an important role in stabilizing tobacco prices at the auction floors. Crop forecasting is the art of predicting crop yields and production before the harvest actually takes place, typically a couple of months in advance [2]. Zimbabwe mostly relies on crop statistical forecasting/estimation, crop reports/field visits from extension officers, and statistical crop forecasts for crop yield forecasts [3]. However, data from crop estimates, which are obtained through surveys conducted after harvests, are in most countries available quite late for early warning purposes.Crop yield estimation in many countries is based on conventional techniques of data collection and ground-based field reports [4]. A variety of mathematical models relating to crop yield have also been proposed in recent years for many crops [4,5]. In Zimbabwe crop surveys are mostly used in estimating crop yield [3]. The method is costly, time consuming, and prone to large errors due to incomplete ground observations, leading to poor crop yield assessment and crop area estimations [4]. Remote Sensing Applications in Crop Area AssessmentRemote sensing is defined as acquirin...

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