Quantitative Loss Estimation of Rice (Oryza Sativa L.) during Harvesting, In-Field Stacking, Threshing and Cleaning in the Akatsi North District of Volta Region of Ghana

ABSTRACT 

The knowledge and perception of farmers in the Akatsi North District of Volta region on harvest and postharvest losses in rice (Oryza sativa L.) during harvesting, in-field stacking, threshing and cleaning were assessed using semi-structured questionnaires. Data were collected on 40 farmers who were selected through a multi-stage, purposive, and simple random sampling methods from September 4 to November 23, 2018. Majority (75%) of farmers interviewed had no formal education on postharvest loss (PHL) assessment of paddy rice. Losses were therefore estimated by speculation, using number of bags as a measure. At least 60% of farmers agreed that the losses at the various points of handling were significant enough to reduce their total output. From the survey, the perceived average yield of farmers was 2.46 Mt/ha. The total perceived loss of farmer was 21.56%. In order to confirm or deny the farmers’ perceived losses of paddy,  a verification field experiment was carried out on 8 farmer fields in three communities, including Ave-Afiadenyigba, Ave-Havi and Ave-Dakpa, to estimate the actual paddy yields and quantitative losses during harvesting, in-field stacking, threshing and cleaning of Jasmine 85 rice variety at two different harvesting times. These were recommended harvesting time at 35 days to harvest after heading (35 DHAH) and farmers’ actual days of harvesting. The field experiment recorded an average yield of 3.77 Mt/ha for the Recommended practice and 3.58 Mt/ha Farmers’ actual practice. The total losses at the two different times (35 DHAH and Farmers’ practice) were 6.38%, 7.65% respectively. To determine the possible changes that may occur in the total grain loss (TGL) across the study area, a Monte Carlos simulation of 10000 trials were performed on each loss variable with Latin Hypercube sampling. The changing scenarios in the TGL were described using a triangular probability distribution model. A sensitivity analysis was performed to determine the loss input variables that are likely to contribute most to the total grain loss.  The probability distribution of losses across the study area at 95% level of significance suggested that farmers who harvest Jasmine 85 variety 35 days after heading are likely to experience paddy loss within the range of 15.9 – 28.7 g/m2 while those harvesting at the farmers’ actual time are likely to encounter total losses ranging from 20.3 - 33.4 g/m2. In general, harvesting was associated with highest paddy loss of 9.96% for farmers’ perceived losses, 2.63 % for 35 DHAH and 3.17% for farmers’ actual losses. However, in-field stacking, with losses of 20.4 – 23.7 g/m2 and 24.9 – 28.6 g/m2 for recommended and farmers’ practices respectively, was identified in the sensitivity analysis as the loss input variable that is likely to contribute most to the total grain loss across the study area. Time of harvesting was however, perceived by farmers as a factor of very high influence on field losses. Reduction in food losses might therefore be achieved through harvesting at 35 days after heading alongside proper postharvest handling practices.