No-Tillage Daikon Production With Weed Cover Mulching As a New Organic Farming System.

Roots vegetables, such as a Daikon, are one of the most major crops in Japan, however, they require more energy for the tillage to reduce soil hardness and compaction. No-tillage with weed cover mulching may be more favorable management to reduce soil hardness without additional energy input for the farming. However little information is available on the root vegetable production system with no-tillage and weed cover mulching. The aim of this experiment is to clarify vegetable yield, soil carbon and nitrogen dynamics in no-tillage and weed-cover mulching.

The experiment was conducted from Oct. 2009 to Dec. 2012 in the center for field science research and education, Ibaraki University, Japan. Experimental design was consisted of two tillage and weed management treatments (NT: no-tillage and weed cover mulching, CT: conventional tillage and clean weeding) and two fertilizer treatments (OF: 100kgN organic fertilizer, NF: no-fertilizer) with 4 replications. As autumn crop, Radish (Daikon), Shougoin and Turnip were cultivated in 2011 and 2012. While rotary tillage was conducted prior to the seeding in CT, NT was managed by no-tillage and allowed to grow the main crops with weed mulch.

The yield of Turnip in 2011 and Radish in 2012 produced in NT were significantly higher than that in CT. However, nitrate content of vegetable root in NT were significantly lower than that in CT, indicating better vegetable quality in NT.

Weed biomass, carbon and nitrogen content in NT were significantly higher than that in CT, which contributed to the increased soil carbon content in the soil surface of NT. With the increase of soil carbon, both soil inorganic nitrogen and soil porosity has increased in NT, but not in CT.

Therefore, it was clarified that weed played an important role in maintaining soil fertility and improving soil physical properties by supplying residual organic matter.