厩肥施用水準が飼料作物の化学成分と飼料価値に及ぼす影響-1-青刈トウモロコシ Studies on Effect of Manure Application upon Chemical Composition and Feeding Value in Forage Crops : 1. Soiling Corn

本研究は厩肥と尿の施用水準が青刈トウモロコシの化学成分と飼料価値に及ぼす影響を究明する目的で行った。試験区の設定に当たって,A区を対照区,B・C区を試験区とした。対照区は施肥基準に基づき化学肥料を施用し,試験区は厩肥と尿をそれぞれアール当たり5,000kg:2,000kg,15,000kg:6,000kg施用し,前者をB区,後者をC区とした。B区のP_2O_5補足には過石を施用した。青刈トウモロコシ(品種名:ホワイトデントコーン)は播種量10アール当たり10kg,うね幅60cmで6月5〜6日に播種した。なお,本草の刈取りは雄花抽出後から乳熟初期に行った。消化試験には青刈トウモロコシの生草,天日乾草及びサイレージを用い,メン羊に給与した。1.4ヵ年の青刈トウモロコシの10アール当たり乾物重は各処理区とも1973年値が最も高かった。しかし,乾物重についてはどの年も処理間に有意差は認められなかった。2.粗蛋白質含量は窒素施用量の多いC区が最も高く,1972年値はC・A区とB区,他の年次はC区とA・B区との間にそれぞれ有意差(p<.01)が認められた。3.粗灰分含量は経年的に増加が認められた。4.Ca含量は厩肥・尿の施用量の多い区が低かった。5.KとNO_3-N含量は厩肥と尿の施用量の多い区が高かった。前者では各処理区とも経年的増加が認められるとともに,1975年値のC区が高くA区との間に有意差(p<.01)が認められ,後者では1974年値のC・B区が高くA区,1975年値はC区が高くA・B区との間にそれぞれ有意差(p<.05)が認められた。6.Na含量は経年的に各処理区とも低下の傾向を示した。7.P含量は1972年を除いて厩肥・尿施用区が高く,1973年はB区とC・A区,1974・1975年はB・C区とA区との間にそれぞれ有意差(p<.05)が認められた。8.生草・天日乾草及びサイレージの化学成分消化率比較をすると,それぞれの処理間でA区の粗蛋白質消化率が量も低く,生草・天日乾草のB・C区とA区との間に有意差(P<.05)が認められた。9.各処理区のサイレージ品質は評点優であった。10.青刈トウモロコシに厩肥・尿の連続多量施用を行った場合,刈取時期が雄花抽出期以後であれば硝酸中毒の危険は少ないが,経年的にK含量の増大が著しかった。

This study was conducted to compare the effects of three levels of manure and urine applications on the chemical composition and the feeding value of soiling corn (white dent corn) during four years, from 1972 to 1975. Levels of application per 10 a during one cropping period were ; High level plot: manure 15,000kg plus urine 6,000kg Low level plot: manure 5, 000kg plus urine 2,000kg Control plot: No manure and urine, N 23kg as ammonium sulphate, P_2O_5 17kg as superphosphate and K_2O 24kg as potassium chloride. Corn plant was sown at the rate of 10kg per 10 a in 60cm rows on Jun. 6 in 1972, and on Jun. 5 in 1973, 1974 and 1975, respectively. Harvesting was made on Aug. 13 in both 1972 and 1973, on Aug. 8 in 1974 (early milk stage), and Jul. 31 to Aug. 13 in 1975 (tasseling to early milk stage), respectively. Digestibility was estimated by the conventional collection digestion trial with sheep. All materials were chopped into 5 to 7cm, and fed to sheep as green forage, sun-cured hay or silage. The results are summarized as follows: 1. During four experimental years, the highest annual dry matter yield was obtained in 1973, while no significant difference was observed between treatments. 2. Crude protein content of the high level plot was the highest throughout experimental years, especially higher than other treatments in 1973, 1974 and 1975. Also, crude protein content of the control plot was significantly higher than that of the low level plot in 1972. 3. Crude ash content of all treatments showed a tendency to increase as experimental year advanced. 4. Calcium content was decreased with increasing manure and urine application. 5. Both K and NO_3-N contents were increased with increasing manure and urine application, though K content showed a tendency to increase with year advanced. Content of K in the high level plot was significantly higher than that of the control plot in 1975. Nitrate nitrogen contents of both high and low level plots were significantly higher than that of the control plot in 1974, while that content of the high level plot was significantly higher than those of other plots in 1975. 6. Sodium content of all treatments showed a tendency to decrease as year advanced. 7. Phosphorus content of the low level plot was significantly higher than those of other plots in 1973, although those of both high and low level plots were significantly higher than the control plot in 1974 and 1975, respectively. 8. In comparisons with digestibility of each chemical composition in green forage, sun-cured hay and silage, digestibility of crude protein in both high and low level plots showed to be significantly higher than that of the control plots in green forage and sun-cured hay, respectively. 9. Silage qualities of all treatments were ranked excellent grade.