ABSTRACT

Grains may be lost in the pre-harvest, harvest, and post-harvest stages. Pre-harvest losses occur before the process of harvesting begins, and may be due to insects, weeds, and rusts. Harvest losses occur between the beginning and completion of harvesting, and are primarily caused by losses due to shattering. Post-harvest losses occur between harvest and the moment of human consumption. They include on-farm losses, such as when grain is threshed, winnowed, and dried, as well as losses along the chain during transportation, storage, and processing. Important in many developing countries, particularly in Africa, are on-farm losses during storage, when the grain is being stored for auto-consumption or while the farmer awaits a selling opportunity or a rise in prices this paper reviews the natural and physical causes of post-harvest losses; in quality, ins weight as well as economically.

CHAPTER ONE

1.0       INTRODUCTION

Current world population is expected to reach 10.5 billion by 2050 (UN March, 2013), further adding to global food security concerns. This increase translates into 33% more human mouths to feed, with the greatest demand growth in the poor communities of the world. According to Alexandratos and Bruinsma (2012), food supplies would need to increase by 60% (estimated at 2005 food production levels) in order to meet the food demand in 2050. Food availability and accessibility can be increased by increasing production, improving distribution, and reducing the losses. Thus, reduction of post-harvest food losses is a critical component of ensuring future global food security.

Food and Agriculture Organization of U.N. predicts that about 1.3 billion tons of food are globally wasted or lost per year (Gustavasson, et al. 2011). Reduction in these losses would increase the amount of food available for human consumption and enhance global food security, a growing concern with rising food prices due to growing consumer demand, increasing demand for biofuel and other industrial uses, and increased weather variability (Mundial, 2008; Trostle, 2010). A reduction in food also improves food security by increasing the real income for all the consumers (World Bank, 2011). In addition, crop production contributes significant proportion of typical incomes in certain regions of the world (70 percent in Sub-Saharan Africa) and reducing food loss can directly increase the real incomes of the producers (World Bank, 2011).

Over the past decades, significant focus and resources have been allocated to increase food production. For example, 95% of the research investments during the past 30 years were reported to have focused on increasing productivity and only 5% directed towards reducing losses (Kader 2005; Kader and Roller 2004; WFLO 2010). Increasing agricultural productivity is critical for ensuring global food security, but this may not be sufficient. Food production is currently being challenged by limited land, water and increased weather variability due to climate change. To sustainably achieve the goals of food security, food availability needs to be also increased through reductions in the post-harvest process at farm, retail and consumer levels.

Food losses do not merely reduce food available for human consumption but also cause negative externalities to society through costs of waste management, greenhouse gas production, and loss of scarce resources used in their production. Food loss is estimated to be equivalent to 6- 10 percent of human-generated greenhouse gas emissions (Gustavasson, et al. 2011; Vermeulen, et al. 2012). A significant contributor of this problem is through methane gas generation in landfills where food waste decomposes anaerobically (Buzby and Hyman, 2012). The US Environmental Protection Agency reports that in the United States about 31 million MT of food waste accounted for 14% of the 2008 solid waste produced in the country (EPA, 2011) costs roughly 1.3 billion dollars to landfill (Schwab, 2010; Buzby and Hyman, 2012). This is cost to the society through utilities bills and taxes.

A study by Institute of Mechanical Engineers indicates that that current agricultural practices use 4.9 Gha (global hectares or 4931 million hectares) of the total 14.8 Gha (14894 million hectares) of land surface on the earth (Fox and Fimeche, 2013). Agricultural production in addition uses 2.5 trillion m 3 of water per year and over 3% of the total global energy consumption (Fox and Fimeche, 2013). With estimated food losses of about 30-50 % of total production, this translates to wasting 1.47-1.96 Gha of arable land, 0.75-1.25 trillion m3 of water and 1% to 1.5% of global energy (Fox and Fimeche, 2013).

Given the significant role food loss reductions could have toward sustainably contributing to global food security, it is important to have reliable measures of these losses. Unfortunately, most of the available postharvest loss and food waste estimates are based on the anecdotal stories with few actual measured or estimated numbers. Moreover these numbers, in turn, feed into estimates of food availability which are widely used in food security assessments and policy analyses. For example, FAO’s Food Balance Sheet provides data for most food security and consumption analyses across the world (http://faostat.fao.org/site/354/default.aspx) and presents a comprehensive picture of a country's food supply during a specified reference period. Food supply available for human consumption is obtained by deducting from total supplies the quantities exported, fed to livestock, used for seed, and losses during storage and transportation. The food loss estimate in the Balance Sheet is currently calculated using an ad hoc methodology. A robust accounting of food losses which is updated regularly will improve the overall data in the Food Balance Sheet and provide more reliable information for analyses and policy making.

In light of this need, this paper illustrates a conceptual model which will support the development of a template for estimating the post-harvest losses in different staple crops. This paper is divided into four main sections- the first section defines food loss and food waste, the second section discusses the factors responsible for the current food loss situation in different parts of world, and the third section talks about measurement problems, and existing methodologies. The final section of this paper proposes a conceptual model that aims at strengthening future PHL estimates.

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