Organic compounds with high Ni content: Effects on soil and strawberry production

Composto orgânico com altos níveis de Ni: Efeitos no solo e na cultura de morango

ABSTRACT

The use of organic residues can improve soil chemical and physical conditions and plant growth. However, these residues often contain heavy metals that can interfere with growth. Here, a pot experiment was performed to compare the effects of organic compound (OC) containing a high nickel (Ni) load with those of a mineral Ni source (NiCl₂, a soluble salt) on the production, quality and nutritional status of strawberry and on soil chemistry. Six dosages of Ni (0, 9, 18, 36, 72 and 144 mg kg^-1) were added to the soil using both OC and NiCl₂. The use of high-Ni OC resulted in increased productivity and fruit weight, whereas the soluble NiCl₂ salt caused reduction in fruit weight. Application of NiCl₂ at concentrations >18 mg kg^-1 also caused internerval chlorosis on leaves, suggesting that strawberry is highly sensitive to Ni. The mineral Ni source was almost 15-fold more effective than the organic source at increasing leaf Ni content. Application of OC caused an increase of organic matter, Ca, sum of bases, cation exchange capacity, base saturation, Zn, Mn, and Cu, but reduced the levels of Mg in soil.

Key words:
heavy metals; phytotoxicity; biosolids; residues