Thuita M, Vanlauwe Bernard, Mutegi E, Masso C
International Institute of Tropical Agriculture, PO Box 30772-00100, Nairobi, Kenya.
Agric Ecosyst Environ. 2018 Jul 1;261:153-160. doi: 10.1016/j.agee.2018.01.007.
Soybean grain yields in sub-Saharan Africa have remained at approximately 50% below those attained in South America despite numerous efforts. A study was conducted in Siaya County (western Kenya) involving 107 farms with soils of different fertility status. The main objective was to test combinations of two inoculants (Legumefix and Biofix) and nutrient sources (Minjingu and Sympal) to raise soybean grain yields. Inoculation used Legumefix or Biofix with and without Minjingu or Sympal in a factorial design. There was soil acidity and a widespread deficiency of potassium, nitrogen, and phosphorus. Inoculation and nutrient source led to increases in nodulation and nodule occupancy. For grain yields the response varied from nil in some sites to high increases in others. Highest grain yields (3000-4000 kg ha) were obtained with Legumefix + Sympal (12% of the farmers testing it). The formulation of the nutrient source was important to meet other nutrient deficiencies in most of the soils. Farmers using Legumefix + Sympal require yield increases of 35% for profitability (Value cost ratio of 3) while farmers using Minjingu + inoculant require a yield increase of at least 68%. Inoculants used alone were most profitable but this is advisable only when farmers are too resource constrained to afford fertilizer. For sustainable yields Legumefix + Sympal or Biofix + Sympal were recommended.
尽管付出了诸多努力，但撒哈拉以南非洲地区的大豆产量仍比南美洲低约50%。在肯尼亚西部的锡亚亚县开展了一项研究，涉及107个农场，这些农场土壤肥力状况各异。主要目的是测试两种接种剂（固氮菌剂和生物固氮菌剂）与养分来源（明金古肥料和Sympal肥料）的组合，以提高大豆产量。接种采用固氮菌剂或生物固氮菌剂，搭配或不搭配明金古肥料或Sympal肥料，采用析因设计。存在土壤酸度问题，钾、氮和磷普遍缺乏。接种和养分来源使根瘤形成和根瘤菌占据率增加。对于谷物产量，不同地点的反应各不相同，有些地点毫无增产效果，而有些地点增产显著。使用固氮菌剂+Sympal肥料时获得了最高谷物产量（3000 - 4000千克/公顷）（测试该组合的农民占12%）。养分来源的配方对于满足大多数土壤中的其他养分缺乏情况很重要。使用固氮菌剂+Sympal肥料的农民要实现盈利（价值成本比为3），产量需提高35%，而使用明金古肥料+接种剂的农民产量至少需提高68%。单独使用接种剂利润最高，但只有在农民资源极度有限无力购买肥料时才建议这样做。为实现可持续产量，推荐使用固氮菌剂+Sympal肥料或生物固氮菌剂+Sympal肥料。
