90 % yield increase of red pepper with unexpectedly low doses of compost soluble substances

Composts are potential substitutes of mineral fertilizers for sustainable agriculture. Composts are commonly applied to soil at high dose, e.g. from 20 to 30 t (dry matter) per ha and year, to compensate organic matter loss and nutrient depletion. Recently, amendment of soluble substances from urban compost at a much lower dose of 1.55 t per ha enhanced tomato productivity much more than the compost itself. Here, we studied the effect of soluble substances at 0-700 kg per ha on red pepper. We measured productivity, chlorophyll, and soil chemical composition. The most remarkable result is an observed maximum productivity for only 140 kg per ha of compost soluble substances. The increases amounted to 90 % for the precocious crop yield, to 66 % for the total crop production, and to 17 % for the per fruit weight. The discovery that the highest effects occur at such low treatment dose is very promising to enhance crop productivity in a sustainable way. No detectable change of soil chemical composition was observed.