In order to alleviate the shortage of fertilizers, the DPR Korea Government has placed considerable emphasis on the use of organic fertilizing materials such as compost, based on utilization of animal, crop and human wastes. In addition, other alternatives such as ash are used as a source of potash.
The limited availability of biomass and the reduced population of livestock are constraints for the production of organic manures. Large quantities of organic fertilizers (10 to 20 t/ha of compost) are used but the quality is doubtful. The raw material consists mostly of straw, household wastes, slag, ash and soil. Animal wastes are scarce since the animal population has fallen in recent years.
It was observed at the cooperative farms visited that 10 to 20 tonnes of compost and 500 to 1 000 kg of ash per hectare had been applied to the summer crop at the time of sowing. Composting is an important activity in DPR Korea. To increase the adoption of composts, the construction of cemented/tiled compost pits along with shade would be beneficial.
The planting of a food legume, harvesting the pods prior to full maturity and turning in the biomass into the soil when still green could be a better economic proposition than a solely green manure crop e.g. peas (pods plus stems) followed by rice. Spring peas offer a good potential for both a pea crop and for green manuring. In field trials, yields of up to 1.5 t/ha of peas have been obtained. Investigation of crops such as mungbean, which also may serve as dual source of grain as well as green manure, may be worthwhile.
Cropping sequences with green manure crops such as spring oats (Chinese variety: Jin Yan Za), common vetch (Chinese variety: Jian She Wandu), red clover and peas have been tried in the province of North Hwanghae.
EM (Effective Micro-organisms) products are 'bio-fertilizers' imported from Japan. Usually, EM is recommended more for vegetable crops than for other crops. However it was noted during monitoring visits that, in many cases, spring crops had nevertheless received 20 kg of EM at the time of sowing and would receive another 100 kg of EM at the following stages of crop growth.
