Nutrient Balance in Organic Raspberry Production with Dairy-manure Amendments

Raspberry (Rubus ideaus) is a perennial crop that reaches commercial production after 4 to 5 years since planting. To improve of Raspberry crop production, fertilizers and manures are applied to the soil. Many farms in the Andean-Patagonian region produce organic crops, and apply manure obtained from complementary activities. A nutrient balance was studied in a raspberry crop amended with dairy manure since a decade by comparing continuously amended plants with respect to plants where amendment was suppressed. Soil nutrient concentrations of the crop area were compared with a nearly non-cultivated soil. The manure had a strong effect on phosphorus (P-Olsen), values being much higher than in pristine soils, around 60 mg kg-1, considered limit value to avoid soil P movement. The concentration in raspberry leaves exceeded 7 g kg-1 and 24 g kg-1 for K and N, respectively. There was a strong increase in the nutrient uptake from flowering to ripeness according to an increase of dry matter from 2196 kg ha-1 to 4791 kg ha-1. A slight dilution effect (nutrient concentration declines as the crop grows) of N, P and K in plants was observed. The nutrients added by the manure and nutrients returned to the soil by pruning resulted in a positive balance. A reduction of the quantities of manure may be applied in the last years of raspberry crop production.