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Wheat straw chopper is a resource conservation technology that makes chaff from combine-harvested wheat straw and saves the environment from smoke pollution, if straw is burnt in the field. Field performance of this technology has not been evaluated yet, although this technology has been adopted in Pakistan for many years. The objective of this study was to evaluate the performance of an improved version of wheat straw chopper in combine-harvested wheat fields of southern Punjab and to determine the economics of this machine. Five test plots ranging from 0.39 to 0.61 ha were selected to determine the performance of this machine. Results revealed that a 75 hp tractor was suitable for operating this machine. Average operating speed of chopper was 2.7 km h-1. Average effective field capacity of chopper was 0.40 ha h-1 and field efficiency was 67.9%. Amount of chaff recovered was 2404 kg ha-1 and chaff recovery from straw was 61.1%. The operating cost of chopper setup was Rs. 5,262 ha-1. Total worth of recovered chaff was Rs. 24042 ha-1 (@ Rs. 10 kg-1). Net gain in terms of recovered wheat straw was Rs. 18780 ha-1. The break even point (use) of this machine for harvesting own fields and rental fields was 77 h (31 ha) and 266 h (105.5 ha), respectively. Wheat straw chopper is a profitable technology that is getting momentum in combine-harvested wheat fields of the country, which saves chaff for cattle feed and increases the benefit of the farmer. [ABSTRACT FROM AUTHOR]

A considerable amount of rice grains is wasted every year in Pakistan because of unavailability of postharvest drying and processing technologies. About 70% of the rice produced in the country is dried through sun heat. which is one of the major causes of reducing head rice recovery during the milling operation. Recently, cross-flow rice dryers have been adopted in the rice milling industry of the country. The heat source of these cross-flow dryers can be a gas or rice husk. This study focussed on the performance evaluation of cross-flow rice dryers with both gas and rice husk heat sources. The experimental results indicated that drying air temperature of the gas-fired and rice husk-fired dryers was 54° and 66°C, respectively. However, the average air flow rate was 6.24 and 2.60 m³ s-1 of gas-fired and rice husk-fired cross-flow dryers, respectively. The drying rate of gas-fired dryer was 2.0 percentage point h-1, whereas the drying rate of rice husk-fired dryer was 1.0 percentage point h-1. The drying costs of gas-fired and rice husk-fired dryers were about Rs. 0.21 and 0.16 kg-1. The overall performance of the gas-fired dryer was satisfactory, while that of the rice husk-fired dryer can be improved by incorporating an appropriate heat exchanger. [ABSTRACT FROM AUTHOR]