Investigation of Effective Irrigation Strategies for High-Density Apple Orchards in Pennsylvania

Xiaohu Jiang,Long He

doi:10.3390/agronomy11040732

Abstract

Irrigation helps grow agricultural crops in dry areas and during periods of inadequate rainfall. Proper irrigation could improve both crop productivity and produce quality. For high density apple orchards, water relations are even more important. Most irrigation in tree fruit orchards is applied based on grower’s experience or simple observations, which may lead to over- or under-irrigation. To investigate an effective irrigation strategy in high-density apple orchard, three irrigation methods were tested including soil moisture-based, evapotranspiration (ET)-based and conventional methods. In soil moisture-based irrigation, soil water content and soil water potential sensors were measured side by side. In ET-based irrigation, daily ET (ETc) and accumulated water deficit were calculated. Conventional method was based on the experience of the operator. The experiment was conducted from early June through middle of October (one growing season). Lastly, water consumption, fruit yield and fruit quality were analyzed for these irrigation strategies. Results indicated that the soil moisture-based irrigation used least water, with 10.8% and 4.8% less than ET-based and conventional methods, respectively. The yield from the rows with the soil moisture-based irrigation was slightly higher than the other two, while the fruit quality was similar. The outcome from this study proved the effectiveness of using soil moisture sensors for irrigation scheduling and could be an important step for future automatic irrigation system.

Highlights

The water consumed under soil moisture-based irrigation was 10.8% and 4.8% less than these of ET-based and conventional methods, respectively
Precision irrigation methods consumed less water compared with conventional irrigation
An irrigation scheduling algorithm was developed with a water balance model tuned by capacitance-type soil moisture sensors and the results showed that the water use in small canopy trees was 24% less when comparing to ET irrigation [28]

Summary

Introduction

Pennsylvania is the fourth largest apple producing state in the country and a commercial producer of many other tree fruit crops including peaches, nectarines, pears and cherries [1]. In Pennsylvania, the precipitation averages 940 mm each year, with 330 mm of this precipitation running off directly into streams, while 610 mm infiltrates the soil where it may be used by crops [2]. Uneven precipitation may cause plant stress during critical growth periods affecting both crop productivity and quality. Most tree fruit orchards require supplemental irrigation to minimize plant stress and increase yield and/or quality. When poor tree growth in a newly planted orchard results from inadequate water availability, maximum cropping may be delayed for years, peak investment is increased by 20% and total profits could be reduced by 66% over the 20-year life of the orchard [3]

Objectives

Methods

Discussion

Conclusion