Potential and Actual Water Savings through Improved Irrigation Scheduling in Small-Scale Vegetable Production

Abstract

Appropriate irrigation scheduling for efficient water use is often a challenge for small-scale farmers using drip irrigation. In a trial with 12 farmers in Sébaco, Nicaragua, two tools to facilitate irrigation scheduling were tested: the Water Chart (a table indicating required irrigation doses) and tensiometers. The study aimed at evaluating if and to what extent simple tools can reduce irrigation water use and improve water productivity in drip-irrigated vegetable (beetroot; Beta vulgaris L.) production compared with the farmers’ usual practice. Irrigation water use was substantially reduced (around 20%) when farmers irrigated according to the tools. However, farmers did not fully adhere to the tool guidance, probably because they feared that their crop would not get sufficient water. Thus they still over-irrigated their crop: between 38% and 88% more water than recommended was used during the treatment period, resulting in 91% to 139% higher water use than required over the entire growing cycle. Water productivity of beetroot production was, therefore, much lower (around 3 kg/m3) than what can be achieved under comparable conditions, although yields were decent. Differences in crop yield and water productivity among treatments were not significant. The simplified Water Chart was not sufficiently understandable to farmers (and technicians), whereas tensiometers were better perceived, although they do not provide any indication on how much water to apply. We conclude that innovations such as drip irrigation or improved irrigation scheduling have to be appropriately introduced, e.g., by taking sufficient time to co-produce a common understanding about the technologies and their possible usefulness, and by ensuring adequate follow-up support.

Sensor Based Irrigation Management in Crop Production: A Review

“…"Effect of irrigation by tensiometer and potassium fertigation rate on water use efficiency of pea and reported highest water use efficiency under the treatment TM1: Tensiometer 75% of FC, 100% potassium fertilizer and they also observed highest dry seed yield in treatment TH2: Tensiometer 85% of FC, 75% potassium fertilizer" [7]. "Higher yield with reduction in water use in the water chart and tensiometer treatments compared with the control treatment over the entire growing cycle of beetroot" [8].…”

Requirements for Sustainable Irrigated Agriculture

“…Like for the other irrigation systems, several studies addressing the adaption and optimisation of drip irrigation strategy have been published in recent years. Common approaches for developing and improving irriga-tion management include calculating crop water requirements (e.g., [62]), monitoring soil water status (e.g., [63,64]), combining soil water balancing and soil sensing (e.g., [65,66]), and monitoring canopy temperature (e.g., [67,68]). Also, an experimental approach involving cosmic-ray neutron sensing for drip irrigation scheduling can be found in recent literature [69].…”

“…Agronomy 2021, 11, x FOR PEER REVIEW 13 of 21 [65,66]), and monitoring canopy temperature (e.g., [67,68]). Also, an experimental approach involving cosmic-ray neutron sensing for drip irrigation scheduling can be found in recent literature [69].…”

Delineation of Soil Moisture Potentials and Moisture Balance Components

“…Under this scenario, the available soil moisture of Indo-Gangetic Plains is described by ψm [15]. Locally fabricated, low-cost tensiometers [16] that could delineate soil matric potential are generally preferred by the farmers for scheduling irrigation more particularly to rice [17,18]. According to Kukal et al [19], increasing suction values to 2000 and 2400 AE 200 mm reduced the land productivity of the rice than earlier recommendation (2-day interval), which mean drying of soils to certain extent saves significant irrigation water without significantly affecting grain yields.…”