Use of compost to manage Fe nutrition of pear trees grown in calcareous soil

Abstract

The aim of this study was to evaluate the effectiveness of soil applied compost in preventing Fe chlorosis of pear trees. The effect of the treatment was evaluated in field conditions on tree growth, nutritional status, yield, fruit quality and soil parameters. A 3-year long field trial was carried out in a mature commercial pear orchard of the cv. Abbé Fétel grafted on quince (Cydonia oblonga) BA29 located in the South Eastern Po Valley (Italy). In a completely randomized block design (5 replicates), including an untreated control, the following soil-applied treatments were compared: (i) Fe chelates (1.65g Fetree−1year−1 as Fe–EDDHA) applied yearly and split in two applications in spring; (ii) organic amendment (compost) applied yearly at a rate of 12kgfwtree−1 at bud break. Leaf Fe concentration and green color were increased by soil applied Fe chelate and, from the second season, by compost. Considering the whole experiment data of leaf Fe concentration and SPAD index showed a positive (P≤0.001) linear correlation (r=0.84). The supply of Fe chelate decreased significantly leaf K, Mn, fruit K and Cu concentration as well as fruit weight but raised tree yield. Compost showed intermediate values of tree crop load and higher fruit weight in comparison to Fe chelate. Iron deficiency reduced fruit sucrose and total carbohydrates concentration. Only compost addition stimulated soil microbial C biomass. Results demonstrate that composted organic wastes yearly applied improved Fe nutrition of pear trees grown in calcareous soils.