Humic Substances Generally Ineffective in Improving Vegetable Crop Nutrient Uptake or Productivity

  • Timothy K. Hartz, Thomas G. Bottoms
  • Published 2010


Soil application of humic acid (HA), generally derived from leonardite shale, is a common practice in California vegetable production. Five commercial HA formulations were evaluated for their effects on soil microbial activity, seedling emergence, crop productivity, and nutrient uptake when applied to representative agricultural soils. Two soils differing… (More)

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