Study on the sand and \u22bota\u22 culture of muskmelon in green house

In order to increase labor productivity, sand culture farming in the green house has been proposed by some workers in horticulture. But there is only a few reports about this problem, and satisfactory standard technique has not yet been established in this culture. Application of \u22Bota\u22 as a bed has been proposed for the green house farming, because of its similarity to sand in physical structure and low content of plant nutrients. Purpose of this study is to establish a standard technique of cultivation of muskmelon by sand and \u22Bota\u22 culture from the stand-point of fertilization. In the first experiment, muskmelon was grown by sea s and from Saitozaki coast, \u22Bota\u22 from Shime coal-mine and soil from the paddy field in Kyushu University Farm, in spring, and liquid chemical fertilizer (Sumitomo ekihi) was used. This fertilizer contains urea, super phosphate and potassium chloride, but does not contain CaO, MgO and trace elements for plant. At the early stage, growth of melon in sand and \u22Bota\u22 was markedly retarded as compared with that in soil culture. Dry matter production and qualities of the melons in sand and \u22Bota\u22 culture was inferior than in soil culture. Contents of ammonium-nitrogen, total nitrogen, soluble nitrogen and P_2O_5 in leaves of melon were higher and contents of CaO, MgO and K_2O were lower in the sand culture than in the soil culture. Content of NH_4-N in soil solution was markedly high and nitrification was checked in sand and \u22Bota\u22 culture. These conditions of melon in sand culture are similar to that of plant growth disturbed by high concentration of NH_4-N in water culture. In the second experiment carried out on the basis of results obtained in the first experiment, melon was grown by liquid chemical fertilizer which contained calcium-, potassium-nitrate, ammonium phosphate and magnesium sulphate, but not contained trace elements for plant. The results obtained showed that there were no appreciable difference among sand, \u22Bota\u22 and soil culture in the growth, the quality and the yield. These results show that muskmelon should be grown with liquid fertilizer containing NO_3-N in sand and \u22Bota\u22 cultures in the green houses.労働生産性を著しく高めうる栽培法として,砂栽培が提唱されたが未だに栽培基準の確立をみず,試作成績の報告も皆無に等しかつた.またボタ栽培はボタが粗粒なのと,植物養分の乏しさが砂に類似している意味で砂栽培に準じて考慮されてきたが,これについても研究成績は極めて少ない.故に温室メロンの砂,ボタ栽培について,施肥論の立場から矩見を得るために研究を行なつた.試験区として砂区,ボタ区および対照区として慣行栽培による土耕区の3区を設け,砂区およびボタ区は尿素態窒素主体の液体化成肥料(石灰,苦土は含まず)を使用した.その結果砂区およびボタ区においては初期生育が遅延し,生育量の不足が生じ,その上品質が低下した.植物体内成分の分析を行なつた所,アンモニア,水溶性窒素,全窒素および燐酸濃度が高く,加里,石灰および苦土濃度は低かつた.さらに土壌溶液中のNH_4-N濃度はNO_3-N濃度よりも顕著に高く,硝化作用が抑制されたことが明らかとなつた.以上のことは(1)メロンが培地中からNH_4-Nを高濃度に吸収したことを示しており,砂区,ボタ区のメロンが通常いわれているアンモニア障害を受け,生育に異常を来たしたものと推測される.(2)液肥中に石灰,苦土を含まないために砂では石灰,苦土の含量不足,ボタでは石灰含量が多く,このため苦土欠乏のみが顕著にあらわれた.このような塩基不足は相対的にNH_4-N濃度を高め,アンモニア障害を助長する一原因になつた.(3)アンモニア障害の回避と石灰および苦土の不足をおぎなうため,硝酸態窒素主体の礫耕用配合肥料を使用した.その結果過剰のアンモニアを蓄積することなく,水溶性窒素濃度も高まらず,生育は促進し,品質も向上することが確認された