学位論文 有機系廃棄物を利用した水稲用新肥料と簡易葉色判定技術の開発に関する研究

千田, 野風生

pp.1 - 98 , 2016-03-23 , 新潟大学
内容記述
学位の種類: 博士(農学). 報告番号: 甲第4201号. 学位記番号: 新大院博(農)甲第162号. 学位授与年月日: 平成28年3月23日
新潟県内における未利用バイオマス資源有効活用のために胎内市,十日町市から排出される鶏ふん,きのこ廃菌床を肥料化し水稲用肥料としての肥効性を検証した.(1)「鶏ふん炭化物混合有機質肥料の開発と水稲に対する施肥効果」胎内市の採卵鶏から出る鶏ふんを炭化し,ナタネ油粕,発酵鶏ふんと混合した新規肥料を開発した.同肥料の無機化特性を明らかにし,現地栽培実証試験を行い現地の化成肥料を中心とした慣行施肥体系と生育,収量を比較した.炭化処理で可給態窒素成分の多くが失われたが,リン,カリ成分は濃縮された.新規肥料は反応速度論による無機化予測により,最初から全窒素の30%が無機化した状態で存在し,生育後半までに窒素の約50%が無機化されると予測できた.その結果から施用量は10aあたり210kgと多くなるが,新規肥料は現地慣行施肥と同等の生育および収量が得られ,化成肥料に代替できることが示された.(2)「きのこ廃菌床肥料化と水稲に対する施肥効果」十日町市のエノキタケ生産時に排出される廃菌床からエネルギーと肥料を同時生産する事業に参画した.廃菌床を燃焼し残った灰の肥料としての効果を確認した.造粒灰の物理性と溶解性や,施肥した場合の熔りん,無ケイ酸を対照とした生育等に与える効果の検証を行った.灰肥料は高いリン酸溶解性を持ち,熔りん並みのケイ酸溶解性を示した.また,灰肥料の造粒物は市販粒状肥料と比較した場合,粒径に関係なく破砕硬度が低く壊れやすいという難点があったが機械による散布は問題なく行うことがでた.また,散布の均一性も熔りんと同等であった.栽培試験では化成肥料と比較して草丈,葉色は大きな差はみられないが,分げつがやや抑えられた.その結果収量がやや低下したが,一穂籾数,登熟歩合,千粒重が増加し玄米品質向上の効果があった.またケイ酸吸収も熔りんに準じ,玄米タンパク質含量を低下する効果があり,良食味米生産の効果があった.灰肥料は土性の違いで効果に差が生じ,粘土質の新通圃場に比べると砂壌質の五泉圃場では水稲のケイ酸吸収が少ない傾向であった.しかし,五泉圃場でも灰肥料施用区はケイ酸資材無施用区に比べて,ケイ酸含量が増加し,玄米タンパク質含量が低下する効果が確認できた.(3)「デジタルカメラを利用した水稲群落葉色の評価法」新規肥料の栽培試験において肥料特性として葉色の推移が対照区と異なる場面が生じた.また,2010年の高温登熟による産米品質低下問題を踏まえ,新潟県は後期栄養の管理で産米品質低下を防止する政策を進めてきた.このためには,出穂前の葉色測定が重要であるが,夏季高温下の作業であり,より簡便で軽労な評価手法が求められている.よって,現行の葉緑素計による調査に代わる簡易な葉色診断方法を開発した.画像解析によりデジタルカメラにより撮影した水稲群落の葉色を同時に移し込んだ葉色票から推定した結果と葉緑素計による葉色値を比較した.その結果,最高分げつ期,幼穂形成期,出穂9日前のいずれの時期においても画像解析による推定値と葉緑素計葉色値の間に高い相関がみられた.この手法を五泉地域圃場で行った場合も高い相関が得られ,実際の栽培現場で穂肥判断に役立てることができた.
We helped plan projects for effective organic-waste utilization in Tainai City and Tokamachi City, two cities in Niigata Prefecture implementing the Biomass Town Concept. In Tainai City, we worked on developing a novel fertilizer based on carbonized chicken manure in order to utilize chicken droppings created in the city. The carbonization process decreases the available nitrogen in chicken manure decreases but enriches its phosphate and potash contents, leading us to expect effectiveness in line with that of chemical fertilizers. We developed a pelletized carbide-mixed organic fertilizer by mixing the carbides with fermented chicken manure and rapeseed oil meal. Kinetic analysis demonstrated that the nitrogen mineralization pattern was of a simple parallel reaction, with 50% of the nitrogen content mineralizing during the rice cultivation period. The carbides possessed high citric-acid-soluble fractions of phosphate and potash, which were slowly released into the crops. Next, we conducted empirical trials of the new fertilizer in agricultural fields in Tainai City. Plots cultivated with the new fertilizer achieved growth equivalent to that of control plots from the middle growing period onward, despite some cases of typical stalk number increases being restricted in the initial period. Moreover, no differences were observed in terms of yield or quality with respect to the control plots. In Tokamachi City, we investigated the effective utilization of waste mushroom beds from the cultivation of Flammulina, a special agricultural product of the city. Silicate and phosphate contents were high in the combustion ash resulting from the burning of waste mushroom beds. Compared with a fused phosphate fertilizer, the combustion ash had higher phosphate solubility and comparable silicate solubility. Granulated combustion ash is more frangible than commercially available granulated fertilizers for use in machine spraying; we were nonetheless able to apply it without issue by means of machine spraying by broadcast spreader. Tillers were sometimes obstructed when paddy rice was cultivated with the ash fertilizer, resulting in slightly decreased yield overall. However, 1000-kernel weight and ripening rate increased and unpolished rice quality improved. In addition, application of the combustion ash effectively increased the silicate content of paddy rice compared with use of the fused phosphate fertilizer, and decreased the protein content in the resulting unpolished rice. How effectively rice absorbed silicates from the ash fertilizer depended on soil texture: applying the organic fertilizer in clayey soil resulted in the highest silicate absorption.
When we were cultivating paddy rice while applying the novel fertilizers in these projects in Tainai City and Tokamachi City, characteristic changes in leaf color were sometimes altered in plots where new fertilizers were applied with respect to their changes during typical cultivation. In response to problems of quality deterioration in rice production due to high temperatures during ripening in 2010, Niigata Prefecture advanced measures to prevent such deterioration by means of late-period nutrient supplementation. Measuring leaf color before rice heading is an important step in carrying this out; however, the task is performed in the high temperatures of the summer season, and thus a simple and non-labor intensive evaluation technique is sorely needed. To this end, we developed a leaf-color evaluation technique that is simpler and less labor-intensive than conventional methods. Paddy rice clusters were photographed with digital cameras at a declination angle of 30° in the paddy levees. At the same time, a leaf-color index (Leaf Color Scale) representing a standard leaf color was imprinted onto the bottom of the image. These images were processed, and on the basis of their chromaticity, chlorophyll meter levels estimated from the leaf-color index number. When we applied this evaluation technique during the ear manuring diagnostic period, we successfully predicted leaf color with high precision with respect to the leaves’ actual levels obtained via chlorophyll meter (r=0.964).
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http://dspace.lib.niigata-u.ac.jp/dspace/bitstream/10191/41878/1/h27fak162_a.pdf

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