Study on yield values of two irrigation systems in adult chestnut trees and comparison with non-irrigated chestnut orchard

Abstract

Different types of irrigation systems can be used in chestnut orchards. To understand which one grants higher yield values treatments were applied in adult trees: drip system - TI; micro-sprinkler system - SI; non-irrigated system - NI. The study covers two years in the northeast of Portugal. Irrigation was triggered every time stem water potential was lower than -1.2 MPa. The study considers costs with the equipment, water and labour, and the income from the chestnuts sale. Due to the hotter conditions of 2016 more water was supplied (93 mm) than in 2015 (47 mm). Little more water was furnished in SI (73 mm) than in TI (67 mm). Production was 27% higher in irrigated (48 kg/tree) than in NI trees (38 kg/tree) and in relation to the canopys area (kg/m²) the TI produced 18% and SI 29% more than NI. Annual costs were higher with irrigation (4654, 4549 and 1530 /ha for SI, TI and NI, respectively) but the higher income (22126, 21984 and 16174 /ha for TI, SI and NI respectively) made up for the investment. The profits from irrigated trees can be 22% or 37% higher than in non irrigated ones, for 1 ha or 5 ha, respectively.