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IRRIGATE FOR THE FUTURE

Use soil moisture to determine when fields and orchards need irrigation to avoid overwatering. Different crop types, soil types and weather conditions all affect the amount and frequency of irrigation needed for farms and orchards.

OVERWATERING HURTS YOUR PLANTS AND TREES AND DEPLETES WATER RESERVES!

Why EFFICIENT IRRIGATION BASED ON SOIL MOISTURE matters:

• Big water savings for everyone—agriculture comprises roughly 70% of total water consumption.

• Irrigation scheduling based on soil moisture can generate annual water savings of at least 10% or 103 tons per donum (tons per 1,337.8 m²) based on local studies by SAVE.

• Better water quality with less seawater intrusion. Less pumping protects groundwater reserves.

• Improved crop production, such as sweeter oranges. • Reduced production costs and improved production yields due

to less pumping and optimal watering.

VARY IRRIGATION SCHEDULE WITH SEASONS! In certain orchards, the same amount of water is used to irrigate throughout the year regardless of the actual need of the crops. This contributes to overwatering in the winter as shown in this graph which can harm your crop. Effects of Overwatering on Crop Production:

• Fruit that is less sweet with less pulp, • More soil-borne diseases, • Increased potential for root rot, • Leaching out of nutrients from the soil, • Increased costs for pumping and fertilizer use, and • Ultimately, decreased fruit production.

IRRIGATE BASED ON SOIL MOISTURE,

CROP TYPE & SOIL TYPE!

SOIL TYPES AND WATER-HOLDING CAPACITY Soil type and texture determine how much water is held in the soil, how much water is available for plants to use and ultimately how well they grow. Soil texture indicates the proportions of fine and coarse material making up the soil. The finer the soil, the higher its water-holding capacity. Soil types in Cyprus can be divided into three broad categories with different water-holding capacities:

Light soil: High sand content (coarse material)

Medium soil: High silt content (medium-coarse material)

Heavy soil: High clay content (fine material)

Photos from top to bottom: A modern hydroponic irrigation system; Typical versus recommended irrigation rates; Soil ball method; Soil moisture system with moisture probes and precipitation gauge.

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Local Resources The local agricultural offices, as well as the Turkish Cypriot Chamber of Agricultural Engineers (TCAE), can be a good source of information on specific irrigation guidelines for different soil and crop types. Strong consideration should also be given to growing alternative crops with low irrigation requirements, such as pomegranates, capers, and prickly pears. Contact TCAE for more information on alternative crops and low-flow irrigation systems.

IMPORTANT! Even though heavy soil has the highest water-holding capacity, medium soil has the highest amount of available water for plants. As the soil texture becomes finer as in heavy soils, it is harder for plants to suck the water from the soil, hence resulting in less available water.

MEASURING SOIL MOISTURE Knowing the moisture of your soil helps you determine its irriga-tion needs. Soil moisture can be measured using a variety of methods including soil feel and appearance, soil sampling, ten-siometers and soil moisture probes. Tensiometers are relatively inexpensive and available at certain plumbing or hardware stores in Cyprus. Soil moisture probes, also used in SAVE’s local stud-ies, provide direct readings which can be saved on a computer. Such instruments can also measure rainfall and salinity in soil.

HOW MUCH TO IRRIGATE Different crops require different amounts of water. Some of the water is used for plant growth which is known as transpiration and some is lost by evaporation from the ground. The two terms combined is known as “evapotranspiration,” or the water need of a plant. How much to irrigate then depends on the evapotran-spiration rate for a particular plant AND the soil type. The ta-ble shows recom-mended irrigation rates just based on the three soil types. These irrigation rates further vary by season and by plant type and maturity. For example, orange trees require more water than pomegranate trees. Young trees generally re-quire more water than mature trees.

By adopting irrigation rates based on the specific water needs of your plants, the soil type they are planted in, weather conditions, and by monitoring soil moisture to fine-tune these irrigation rates, you can irrigate efficiently and help save water.

August 2008

Texture Irrigation Rate (cm/hour)

Light (sand) 2.5 – 7.5 Medium (loam) 0.75 – 2.0

Heavy (clay) 0.02 – 0.5

THE GÜZELYURT/MORPHOU SOIL MOISTURE PILOT STUDY To assess potential water savings through efficient irri-

gation practices, SAVE has been conducting a pilot soil moisture study in collaboration with local farmer, Mr. Fuat Bağkur, at his citrus and pomegranate orchards in Bostancı/Zodia.

Mr. Bağkur has his own well and a drip irrigation sys-tem, giving him full control over the watering schedule which was already calibrated based on crop type and soil type, but not checked against actual soil moisture. As part of the pilot study, moisture probes were installed next to selected pomegranate and citrus trees in three types of soil—light, medium and heavy. At each location, a combined salinity, temperature, and moisture probe was placed approximately 15cm below ground surface (bgs), and moisture probes were placed at 30 and 50cm bgs. Data were collected from the probes at regular intervals.

An analysis of the soil moisture data is presented in the graph above for the citrus orchard with medium soil. SAVE used FAO’s CROPWAT software to estimate recommended soil moisture levels, or irrigation re-quirements, for this soil and tree type (blue, green, yellow and red zones). Each peak on the graph indi-cates the increase in soil moisture during an irrigation cycle. Relative to the estimated irrigation require-ments, the data indicated that the trees were being over-watered at least half the time. Better results were seen with the pomegranates. SAVE estimated that 10% or 103 tons of water per donum could be saved annually if the citrus was being irrigated more effi-ciently. Even greater savings could result on farms and orchards not already scheduling irrigation based on soil moisture, crop and soil type.

Source: http://extension.usu.edu

SIMPLE SOIL MOISTURE TEST In most soils, soil moisture can quickly be checked using the “Soil Ball Method.” To do this, dig a small hole and remove a handful of soil from 15 to 30 centimeters deep. Using your hand, squeeze the soil into a ball. Then, open your hand and bounce the ball in the palm of you hand. If it remains in a ball, the soil has enough moisture and does not need watering. If it falls apart, the soil needs watering. It should be noted that this method does not work in light sandy soils.

Key Concepts When you irrigate your soil, excess water drains away, leaving the soil at its field capacity. Now, the soil has available water that can be used by the plants. As the available water is used up by plants and lost to evaporation, the soil moisture reaches a wilting point below which a plant dies.

E-MAIL: SAVE-info@irgltd.com www.save-irg.com TEL: (+90) 392 228 1925 / (+357) 22 770 757 FAX: (+90) 392 228 17 56

ENVIRONMENT ◊ CULTURAL HERITAGE ◊ GEOGRAPHIC INFORMATION SYSTEMS ◊ SMALL GRANTS

Soil is full of water

Water in soil is available to plants

Soil is almost dry

FIELD CAPACITY

WILTING POINT

WATER DRAINS

WATER IS HELD IN SOIL

PLANTS DIE