Guano as a nitrogen source for fertigation in organic farming

Guano is a natural organic fertilizer used in organic farming management when supplementary nitrogen is needed. In modern irrigated agriculture N top dressing is often applied through the irrigation water. The objective of this research was to evaluate the potential of guano as a source of available N when applied through water, compared with application to soil. The release of mineral and total soluble N from guano to water was monitored, as a function of time, under laboratory conditions, and compared with mineralization of guano in soils. The effect of guano:water ratio, aeration of the mixtures, addition of rock-phosphate or clay minerals, and temperature on the composition of the solutions was determined. Guano released more than 90% of its N content into solution during 10 d at a guano:water ratio of 1:10 at 27°C. The release of soluble N, of which 85% was NH₄-N, was linked with an increase of pH from 7.0 to 8.5 or more. None of the treatments increased the rate or the total N release beyond that. Suboptimal temperatures, 13.6 ± 4.7°C or 50°C, greatly reduced the rate of guano-N release to solution. The mineralization of guano in soil was more rapid than in water, but the total N release was the same, leading to the conclusion that the application of guano through the irrigation water may be as efficient as directly to soil, provided sufficient time for fermentation is allowed.Contribution from the ARO, The Volcani Center, Bet Dagan 50250, Israel, no. 3290-E, 1991 series.     

试论现代化肥施用技术

根据普遍使用较大数量化肥是我国现代农业发展的重要标志,指出应用现代施肥技术是提高肥效、减少化肥对生态环境等负面影响的基本途径。提出现代施肥技术的核心和关键在于把化肥施到作物吸收根系的分布区域。阐述现代施肥技术基本原则:把任何化肥都施到作物根系的伸展区域,供作物快速有效吸收;将化肥溶于水制成营养液后随水灌施,能明显提高水、肥的利用率。     

水溶肥中水不溶物含量对滴灌施肥系统过滤器堵塞的影响

研究了不同水不溶物含量的水溶性肥料对滴灌施肥系统过滤器堵塞的影响。结果表明,以膨润土为填充料的供试肥料(膨润土肥料)和凹凸棒土为填充料的供试肥料(凹凸棒土肥料),在水不溶物质量分数为2%以上时43 min内均可使过滤器两端的压力差达到0.05 MPa,并最终使过滤器完全堵塞。