Collection of Millet Germplasm in Sri Lanka and Thailand

雑穀類は, イネ, ムギ等のような多量生産を行う穀類以外を総称していう言葉である。今回の探索収集では, 禾穀類の中の小粒作物 (アワ, キビ, ヒエ等, ミレットと言われる) を中心に, モロコシ, トウモロコシ等も収集した。ミレットは, 古くからユーラシア大陸或はアフリカ大陸において広く栽培され, 受け継がれてきたが, 近年, 生産性や収益性の高い作物に置き代わり, 急速に耕地から姿を消しつつある。今回は, 特にインドを中心としていまなお広く栽培されているシコクビエ, アワ等のミレットを中心に, 数種類の雑穀類をスリランカ及びタイ北部から収集した。収集した系統のほとんどは各地域の農家において古くから栽培されてきた在来種である。本探索により, 48点のシコクビエ (Eleusine coracana), 23点のアワ (Setariaitalica), 6点のキビ (Panicum miliaceum), 8点のモロコシ (Sorghum bicolor), 9点のトウモロコシ (Zea mays) を収集した。また, ミレットとの混作作物或は隣接した畠の作物も一部収集した。全収集数は106点で, そのうち89点はスリランカで, 17点はタイで収集した。中部及び南部スリランカにおいて, 標高Omから約2,000mの地域を延べ1,475kmに渡り探索し, 作物の生育データと共に種子を収集した。スリランカにおいては, 植物遺伝資源センターが独自に探索収集を行っていたので, 同センターの収集リストを照合し, 探索集落に重複を生じないように配慮した。シコクビエは乾燥・半乾燥地帯の焼畑等において広く栽培されていた。収集したサンプルには穂の形や大きさ, 節の色等に変異が認められた。混作が多く, 混作作物にはアワ, ナ類等色々であった。キビの栽培を見かけることは非常に少なく, 主として農家の保存種子の分譲を受けた。豆類等隣接畑から収集したものもあった。シコクビエはいわゆる "うす焼き" あるいはペースト状にして食べるということであった。アワはお粥として食べるのが一般的のようであった。農家は雑穀, 野菜等の作物の種子をよく保存しており, 古くから集落に伝わる在来種が多かった。スリランカには今回を含めても未収集地域が多くあり, 今後とも収集が必要である。北部タイにおいてはミレットの食用としての栽培は急減していた。作期ではないこともあってか, 栽培畑に巡り会うことはなかった。小数部族の集落を訪ね, 農家が保存している穂や乾燥中の穂から種子を収集した。収集物はモロコシ, トウモロコシがほとんどであった。北部タイのミレット収集を計画する場合, 北西部のカレン族, 北東部のリス族等が住む, より深い山岳地帯に足を踏み入れる必要があると考えられた

Comparative analysis of different tillage systems used in sugarcane (Thailand)

In order to reduce the impact of decreasing profit margins in crop production systems, all possible options that will increase net profits need to be explored. Land preparation and stool removal in sugarcane production can be a major contributor to overall production costs. Since estimates that mechanization can contribute as much as 50% of the total production costs, considerable savings can potentially be made if the number of tillage operations is reduced. Such savings however, have to be offset against other costs associated with minimum or no-tillage systems, such as the increased need for herbicide. In addition, conventional tillage systems have been implicated in yield decline over the long-term and therefore yield benefits are envisaged, together with cost savings, by the adoption of minimum and no-tillage sugarcane production. A comparative analysis of five sugarcane tillage systems using data from eight years, showed that minimum tillage, with mechanical stool removal and machine planting gave the best economic returns, being 29.3 and 39.4% more profitable than the conventional and no-tillage treatments, respectively. Other minimum tillage treatments, with sub-soiling and machine / manual planting combinations also performed well. Whilst the no-tillage treatment made substantial savings from the non-use of machinery, these were offset to a large degree by the extra costs associated with herbicide use and extra labour requirements

Ammonia volatilisation from urease inhibitor-treated urea applied to sugarcane trash blankets Volatilização de amônia a partir de uréia tratada com inibidor de urease aplicada sobre palha de cana-de-açúcar

Legal restrictions from burning sugarcane prior to harvest are causing a sharp increase in acreage which is harvested as green cane. The presence of a thick sugarcane trash mulch left after harvest makes it difficult to incorporate fertilisers in the soil. Since large losses of ammonia may occur when urea is surface applied to trash, it is important to find ways to improve urea-N use efficiency. The urease inhibitor NBPT slows down urea hydrolysis and thus may help decrease ammonia losses. Ammonia traps were set up in seven sugarcane fields covered with trash and fertilised with ammonium sulfate or ammonium nitrate, urea, and NBPT-treated urea. All N fertilisers were surface-applied at rates of 80 or 100 kg N ha-1. Very little N was lost when ammonium nitrate or ammonium sulfate were used. However, volatilisation losses as ammonia from the urea treatments varied from 1% (rainy days after fertilisation) to 25% of the applied N. The percentage of reduction in volatilisation due to NBPT application ranged from 15% to 78% depending on the weather conditions during the days following application of N. Addition of NBPT to urea helped to control ammonia losses, but the inhibitor was less effective when rain sufficient to incorporate urea into the soil occurred only 10 to 15 days or latter after fertiliser application.<br>Restrições legais à colheita de cana-de-açúcar com despalha a fogo estão causando um aumento da área cultivada com cana crua. Essa prática gera uma espessa camada de palha de cana sobre o solo após a colheita, o que dificulta a incorporação de fertilizantes. Uma vez que grandes quantidades de amônia podem ser perdidas quando a uréia é aplicada superficialmente sobre a palha, é importante buscar alternativas para maximizar a eficiência de uso do N-uréia. O inibidor de urease NBPT retarda a hidrólise da uréia e pode contribuir para diminuir as perdas de amônia por volatilização. Para quantificar essas perdas, foram instaladas câmaras coletoras de amônia em sete áreas de produção de cana-de-açúcar colhida sem queima; estas foram fertilizadas com sulfato ou nitrato de amônio, uréia ou uréia tratada com NBPT. Todos os fertilizantes nitrogenados foram aplicados superficialmente em doses de 80 ou 100 kg ha-1de N. As perdas de N foram muito pequenas quando se usou nitrato ou sulfato de amônio. Entretanto, as perdas por volatilização de amônia decorrentes do uso de uréia variaram de 1% (com dias chuvosos após a adubação) a 25% do N aplicado. O uso de NBPT proporcionou reduções de 15 a 78% nas perdas por volatilização, dependendo das condições climáticas nos dias posteriores à aplicação de N. A adição de NBPT à uréia ajudou a controlar as perdas de amônia, mas o inibidor foi menos efetivo quando chuvas suficientes para incorporar a uréia no solo ocorreram somente 10 a 15 dias, ou mais, após a aplicação dos fertilizantes

Nitrogen management guidelines for sugarcane production in Australia: can these be modified for wet tropical conditions using seasonal climate forecasting?

Sugarcane is a highly valuable crop grown in tropical and subtropical climates worldwide primarily for the production of sucrose-based products. The Australian sugarcane industry is located in close proximity to sensitive environments and the apparent declining health of the Great Barrier Reef has been linked to damaging levels of land-based pollutants entering reef waters as a result of sugarcane cultivation undertaken in adjacent catchments. Unprecedented environmental scrutiny of N fertiliser application rates is necessitating improved N fertiliser management strategies in sugarcane.Over time the focus of N fertiliser management has shifted from maximising production to optimising profitability and most recently to improved environmental sustainability. However, current N calculations are limited in their ability to match N fertiliser inputs to forthcoming crop requirements. Seasonal climate forecasts are being used to improve decision-making capabilities across different sectors of the sugarcane value chain. Climate is a key driver of crop growth, N demand and N loss processes, but climate forecasts are not being used to guide N management strategies. Seasonal climate forecasts could be used to develop N management strategies for 'wet' and 'dry' years by guiding application rate, timing and/or frequency of N inputs and the benefit of using alternative forms of N fertiliser. The use of seasonal climate forecasts may allow more environmentally sensitive yet profitable N management strategies to be developed for the Australian sugarcane industry