摘要
In order to measure dust's nutrient input on farmland in different agro-ecological zones, Harmattan dust was sampled by mats with plastic straw in Ghana between 2002–2006. The inputs of total nutrients by Harmattan dust in Ghana per Harmattan period were about 1–2 kg Ca ha-1, 0.5–2 kg K ha-1, 0.5–1.5 kg Mg ha-1and less than 0.5 kg P ha-1. Compared with the annual input of nutrients by precipitation, the dust accounted for 10% or less of Ca, Mg and K but approximately 20%–40% of P. The input of nutrients by dust was only valid for areas with vegetation, because in areas with none or sparse vegetation, loss of soil due to wind erosion and hereby loss of nutrients might be significant. In farmland areas with bare and vegetated fields there seemed to be an internal redistribution of the nutrients and not a net gain of nutrients from outside the area(long-range transported dust). The input of P by dust might be of some importance in the traditional shifting cultivation systems, while the inputs of other three nutrients of Ca, Mg and K were so low that they must be considered insignificant. In the intensive agriculture systems with huge inputs of manures and fertilizers the nutrient input by dust is insignificant and could be neglected.
In order to measure dust's nutrient input on farmland in different agro-ecological zones, Harmattan dust was sampled by mats with plastic straw in Ghana between 2002-2006. The inputs of total nutrients by Harmattan dust in Ghana per Harmattan period were about 1-2 kg Ca ha-1, 0.5-2 kg K ha-1, 0.5-1.5 kg Mg ha-1 and less than 0.5 kg P ha-1. Compared with the annual input of nutrients by precipitation, the dust accounted for 10% or less of Ca, Mg and K but approximately 20%-40% of P. The input of nutrients by dust was only valid for areas with vegetation, because in areas with none or sparse vegetation, loss of soil due to wind erosion and hereby loss of nutrients might be significant. In farmland areas with bare and vegetated fields there seemed to be an internal redistribution of the nutrients and not a net gain of nutrients from outside the area (long-range transported dust). The input of P by dust might be of some importance in the traditional shifting cultivation systems, while the inputs of other three nutrients of Ca, Mg and K were so low that they must be considered insignificant. In the intensive agriculture systems with huge inputs of manures and fertilizers the nutrient input by dust is insignificant and could be neglected.
基金
supported by the Danida-Enreca project "Ecological Laboratory" of the University of Ghana, Legon, Accra, Ghana
关键词
养分输入
加纳
营养物质
沉积
西非
稀疏植被
养分投入
农业生态区
deposition rate, dust deposition, input of nutrient, long-range transported dust, nutrient concentration, traditionalagricultural system