2014 Volume 6 Issue 2 Pages 9-21
The use of living mulch is an environmentally friendly farming practice well known by organic farmers and has been recognized by other farmers because of a new agricultural policy to promote sustainable farming in Japan. Living mulch practice is known to be useful in soil conservation, weed control and nitrogen supply, however, the application is limited by type of crops, the high cost of mulch seeds and influence on crop yields. In addition, impacts of living mulch systems on the atmospheric environment are not well known while agricultural fields are a major source of nitrous oxide (N2O) emission, which has 310 times higher global-warming potential than CO2. In order to assess the effectiveness of the living mulch system using low grade wheat grains, impacts on weed control, chemical and physical characteristics of soil and N2O emission from soil were examined.
The field experiments were conducted at two organic farms with different fertilization systems in Ami, Ibaraki and in Nasukarasuyama, Tochigi prefectures, Japan between May and October 2013. Eggplants were planted as a main crop on ridges covered with black plastic mulches, and low grade wheat grains were sown as living mulches in furrows. In Ami, there were four treatments: cattle manure with/ without living mulch, and cattle manure plus coated fertilizer with/ without living mulch. In Nasukarasuyama, two treatments (mixed-organic fertilizer with/ without living mulch) were prepared. These were three replicates for all treatments.
The results showed the furrows with living mulch treatment decreased weed biomass by 20-62% and nitrate concentrations by 50-85% compared to the furrows with no mulch treatment. In the Ami field, N2O emissions from the living mulch treatment were doubled compared to the no mulch treatment, while there was no difference between the treatments in Nasukarasuyama. There were no significant differences among the treatments in the eggplant yield. Above all, we concluded this low cost living mulch system has a very low impact on N2O emission and is effective for weed control and preventing nitrate leaching in organic and reduced chemical fertilization systems without sacrificing the crop yield. Moreover, this practice is 32-62% cheaper than conventional practice or the use of proper wheat seeds in the weeding cost. This system could be a better option for farmers to expand environmentally friendly farming in Japan.
