GUIDELINES FOR SUSTAINABLE HAZELNUT IRRIGATION GUIDELINES FOR SUSTAINABLE HAZELNUT IRRIGATION Table 9. FAO Land Suitability classification (modified). 4.1. Rating table for Halzenut suitability (Control section = 80 cm) Suitability class Rating S1 100 85 S2 S3 N1 N2 65 45 25 0 Weight 300-500 800-1000 <300 >1000 <300 >1000 1 Soil hydraulics The type of soil affects the movement of water, both when it infiltrates and when it is inside. Climate (c) 600-700 500-600 700-800 1-2 3-5 5-10 10-15 >15 1 Medium daily temperature during flowering C° 14-15 12-13 5-12 0-5 <0 2 Rainfall mm in MayJune 200-250 250-350 350-500 >500 >500 2 Rainfall mm/year Frosty days in AprilMay (during flowering) Landscape (t) Slope % Elevation m slm Aspect <5 5-10 10-15 15-25 >25 1 300-500 500-700 200-300 700-900 100-200 >900 <100 >900 <100 1 Flat SE-SO S - NE - E SO - O N - NO N 1 Stoniness (%) <1 1-3 3-15 15-35 >35 1 Rockiness (%) <2 2-5 5-10 10-50 >50 1 Well drained Moderately well drained Somewhat Poorly drained Somewhat excessively drained Poorly drained Excessively drained, very Poorly drained No drainage, Excessively drained 1 Soil (s) Internal drainage Rooting depth (cm) 4.1.1. Infiltration Infiltration refers to the entry of water into the soil. The rate at which water enters is called the infiltration rate. Permeability refers to the percolation of infiltrated water through the soil. An infiltration rate that is less than 3 mm/hour is considered low, while a rate above 12 mm/hour is relatively high. This can be affected by factors such as water quality, physical characteristics of the soil, such as soil texture and type of clay minerals, and chemical characteristics including exchangeable cations. The infiltration rate generally increases with increasing salinity and decreases with either decreasing salinity or increasing sodium content relative to calcium and magnesium, the SAR (sodium adsorption ratio). Therefore, salinity and SAR must be considered together for a proper evaluation of the ultimate effect on water infiltration rate. When the ground slope is >10%, grassing of the inter row is strongly recommended in order to facilitate water infiltration and reduce runoff and erosion, since the infiltration rate reduces as the slope increases. Indicative values are in Table 10. Table 10. Reduction of infiltration rate according to topography Slope (%) Decrease of Vi (%) 0-5 0 6-8 20 9-12 40 13-20 60 >20 75 As a rule, recommendation for grassing the inter row does not apply when total precipitation during spring is <500 mm and the soil texture is from clay to sandy loam clay. >100 70-100 50-70 50-35 <35 2 L, SLC, SiL CL, SL, SC Si, FLA, AL C<60%, LS S, C>60% 1 <5 5-10 10-25 25-35 >35 1 Moderately high 3.6-36 Moderately low 0.36-3.6 Low 0.036-0.36 High 36-360 Very low <0.036 Very high >360 Very low <0.036 Very high >360 1 Wetted diameter AWC mm (available water capacity) >200 150-200 100-150 50-100 <50 2 Both the infiltration rate and the distribution of water within the soil depend primarily on the texture (Figure 8). Water table (cm from surface) >100 80-100 100-50 25-50 <25 1 These characteristics can be reliably established through experimental observation and calculation, according to the following guidelines: 5.5-7.2 5.0-5.5 7.2-8.0 4.5-5.0 8.0-8.5 <4.5 8.5-9.0 <4.5 >9.0 1 <3 3-5 5-9 9-12 ESP 8-15% >12 ESP>15% 1 Texture Coarse fragments (%) Ksat (permeability mm/h) • Fertility (f) pH Salinity ds/m Alcalinity (ESP %) <6 6-10 10-15 >15 >15 1 CEC (meg/100gr) >18 12-18 10-12 5-10 <5 1 Calcium carbonate % <8% 8-15% 15-25% 25-35% >35% 2 <2.5% 2.5-5% 5-8% >8% >8% 2 Active calcium carbonate % 18 4.2. Soil hydrology • • • • lay-out dripper lines (preferably 20 m to 30 m long), on the soil that is to be irrigated, with different inter-dripper spacing; connect the lines to a water source which will provide a continuous and stable supply; switch on the system at the required operating pressure and irrigate for about 12 hours on heavier clay soils, and for about six hours on lighter sandy soils; allow the water to penetrate the soil for a further 24 and 12 hours respectively, without any interference, in order to allow the wet zone to reach its maximum dimensions; dig longitudinal and cross profile furrows and make the necessary observations and measurements to establish whether the proposed system will satisfy all requirements according to established norms (ARC, 2010). 19