冬作にreseeding(自生化)によるサブタレニアン・クローバを栽培し,夏作に飼料用トウモロコシを栽培する体系は,冬作カバークロップの播種作業コストを削減しかつ夏作物での投入窒素の削減が期待できる.本研究では,サブ・クローバのreseedingによる栽培を実施して3年目の圃場と冬作裸地圃場とで飼料用トウモロコシを異なる窒素施肥レベルで栽培し,トウモロコシの収量および吸収窒素を基にサブ・クローバのreseeding管理圃場での投入窒素量の削減とトウモロコシの収量維持との関係を検討した.試験は,不耕起6月播種体系と耕起7月播種体系の二つの栽培体系で1996年から1997年の2年間にわたって検討した.
その結果,サブ・クローバのreseeding管理圃場でのトウモロコシへの窒素の寄与は不耕起6月播種体系で108kg N ha^-1と耕起7月播種体系では88kg N ha^-1であった.この結果は,サブ・クローバが当該年に固定した窒素に加えサブ・クローバのreseeding管理により蓄積された窒素も含むものと考えられた.

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Cover crops may be effective tools for managing the sustainable agriculture, however, tillage systems should be discussed how to introduce cover crops to the farmer's field. In this research, we investigated the performance of rotary tillage in the cover crop fields compared with fallow. Main results are follows.
1) Before rotary tillage, the soil dry densities in the 15-20cm soil depth layer in the cover crop fields were lower than that in the fallow field. After rotary tillage, soil dry densities in the fields of sub clover, crimson clover, and heary betch were almost same as that in the fallow, but that in the rye field was the lowest.
2) After rotary tillage with 3 levels of tilling pitch ranging from 1.0 to 7.0cm, the mean diameters of soil clods in the fields of cover crops were larger than that in the fallow field. One of the reasons was that there were some soil clods with diameter over 32mm in cover crop fields.
3) The problem that the cover crops were wound around the shaft of rotary tiller during tilling was obviously decreased by mowing the cover crop before rotary tillage.
4) After rotary tillage with 1.0cm tilling pitch, 60-70% of the plant bodies of cover crops was buried under the 5cm depth layer of soil in the fields of sub-clover, crimson-clover and heary betch, but that in the rye field was buried only 50%.
5) After rotary tillage with 1.0cm tilling pitch, the emergence ratios of silage corn as a subsequent crop in the fields of sub-clover, crimson-clover and heary betch were over 75%, these values were almost same as that in the fallow field. However, that in the rye field was the lowest.
6) Rotary tillage with 1.0cm tilling pitch after mowing made an appropriate seedbed in the fields of legume cover crops, because legume cover crops did not have so much dry matter and stem strength. Meanwhile, rotary tillage in rye field did not make a good seedbed with any tilling pitch and regardless of mowing treatment. These results suggested that another tillage system should be appropriate in the field of rye cover crop.

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Efficiencies of a hand-held vibrator for harvesting fruit from ‘Tifblue’ (Rabbiteye blueberry) [Vaccinium ashei (Reade)] were investigated in relation to the properties of fruit and force required to dislodge fruit.
It was found that the heavier fruit dislodged quicker than the lighter fruit, it is thought that this is due to increased inertia movement associated with the heavier fruit.
The degree of force required to dislodge the fruit from the pedicel was much the same as one required to dislodge the pedicel from the peduncle in green fruit. In ripe fruit (all blue color), on the other hand, the former was far less than the latter. This indicated that the pedicel, an unwanted item in the market, was separated from ripe fruit more readily compared with green fruit.
Ripe fruit dislodged more readily at a low vibrant frequency than less ripe fruit. Ripe fruit dislodged most efficiently at a 30mm stroke and 7.5Hz frequency, although with this vibration mode almost all the green fruit did not dislodge.
On the other hand, when applying the vibration to the shoot (30mm stroke and 7.5Hz frequency), among the fruit which were dislodged there were a few fruit with pedicels attached which needed to be graded out before shipping to the market. However, there were few ripe fruit among the fruit left on the shoot, and the fruit dislodged were mostly ripe fruit.

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