Technical manual for “Fertigation manual: Open-field crops and date palm" Technical manual for Fertigation manual: Open-field crops and date palm Naeim Mazaherieh Biju George Arash Nejatian Azaiez Ouled Belgacem 2018 1 Technical manual for “Fertigation manual: Open-field crops and date palm" Contents 1. INTRODUCTION .............................................................................................................. 3 ADVANTAGES OF FERTIGATION ...................................................................................... 3 2. DETERMINING CROP WATER USE ...................................................................................... 4 3. PLANT NUTRIENT REQUIREMENTS ...................................................................................... 8 THE UPTAKE PROCESS ................................................................................................. 9 4. FERTIGATION MANAGEMENTS ......................................................................................... 10 THE TARGET YIELD AND CROP NUTRIENTS REQUIREMENTS ................................................. 12 5. FERTILIZERS MANAGEMENT ............................................................................................ 13 BASIC MIXING RULES ................................................................................................ 13 PRECIPITATION ......................................................................................................... 15 SOIL- NUTRIENT SAFETY MARGINS ................................................................................ 15 NUTRIENT SOURCES (FERTILIZERS) ................................................................................ 15 SALT INDEX ............................................................................................................. 15 FERTILIZERS PROPERTIES FOR FERTIGATION ................................................................... 16 APPLYING THE RIGHT AMOUNTS OF FERTILIZER ............................................................... 16 6. SETTING FERTIGATION SYSTEM ........................................................................................ 17 SELECTING AN INJECTOR ............................................................................................. 17 6.1.1. Venturi Bypass ............................................................................................. 17 6.1.2. Metering Pumps .......................................................................................... 18 6.1.3. Hydraulic Units ............................................................................................ 18 .6.1.4 Conventional flow by-pass tank ................................................................... 19 7. FERTIGATION UNDER SALINE CONDITIONS .......................................................................... 19 ELEVATED SALT LEVELS ............................................................................................... 20 NUTRIENT INTERACTIONS ........................................................................................... 20 NUTRIENT UPTAKE RATES AND MOBILITY ....................................................................... 20 8. FERTILIZERS APPLICATION ............................................................................................... 21 SOLUBILITY .............................................................................................................. 21 ACIDITY .................................................................................................................. 24 9. SOIL TESTING ............................................................................................................... 26 ORGANIC MATTER .................................................................................................... 27 DETERMINING NUTRIENT REQUIREMENTS ...................................................................... 27 SOIL CHEMICAL ANALYSIS AS A TOOL FOR EVALUATING NUTRIENT AVAILABILITY. ..................... 27 9.3.1. Soil sampling and analysis ........................................................................... 28 9.3.2. Depth of soil sampling ............................................................................... 28 9.3.3. Method of soil sampling .............................................................................. 28 9.3.4. Interaction of soil analysis results ................................................................ 29 10. DATE PALM FERTIGATION AND FERTILIZATION APPLICATIONS ............................................ 30 FERTIGATION CALCULATIONS .................................................................................. 31 11. REFERENCES ............................................................................................................ 35 2 Technical manual for “Fertigation manual: Open-field crops and date palm" 1. Introduction Fertigation is known as the process of application of nutrients through irrigation systems in certain fixed concentrations according to the actual crops needs from irrigation water and nutrients at the different plant growth stages. This is done through the injection of fertilizers directly into the irrigation network to reach the level of humidity and a constant nutrients concentration in the root zone region. The correct design of the irrigation network is the most important step for applying fertigation technology to ensure high efficiency in the distribution of fertilizer in the root zone region as well as good management and maintenance of the irrigation network operations and injectors fertilizing periodically and regularly is essential to ensure its work efficiently. Advantages of fertigation Nutrient requirement according to crop stages (tea spoon feeding). More uniform distribution and closer to root system. Better availability of nutrients to plants. Nutrient uptake increases. Reduced losses of nutrients by leaching. Preventing damages to roots. Less costly application labor. Less soil compaction. Reduced weed population. Application flexibility (time, weather, soil). Disadvantages The system needs clean water (without solid particles) that may clog the emitters. (Filtration) Knowledge of the chemical composition of water is important to avoid precipitation with the added fertilizers. Sometimes pretreatment is necessary. (Filtration) The system needs equipment's which some of them are expensive. Not all type of fertilizers are suitable for fertigation. What are the things needed to ensure good management of fertigation? Determine the crop water requirements. Good and proper design of the irrigation system. 3 Technical manual for “Fertigation manual: Open-field crops and date palm" Use non-corrosion materials equipment's in fertigation system such as plastic and stainless steel Build up a fertigation program separately for each crop that meets its nutrients requirements according the growth sages. The total concentration of the elements in the main irrigation line must not exceed 5 g / l. Start the injection of fertilizers after sure that water filling all irrigation lines. Carry out maintenance of the fertigation system regularly and systematically 2. Determining Crop Water Use Crop water use is typically expressed in mm of water per day as ETc (evapotranspiration of the crop). It’s typically calculated by multiplying the reference evapotranspiration (ETo) rate, which is generated from daily local weather station data, by the crop coefficient (Kc), which is unique to the crop and the geography where it is grown. The purpose of the Kc is to adjust generic weather information to reflect the specific crop being grown. Weather and crop coefficient data may be obtained from local government or university sources, or may be generated on the farm with proper equipment and research procedures. Table 1 represented the monthly average reference evapotranspiration (Eto) which estimated by using Penman Monteith equation basing on metrological data which collected from metrological weather station during 2013-2015 period at Fujairah (UAE). Table 1. The monthly average Reference Evapotranspiration (Eto) Mon May Aug Sep Nov Dec Feb Mar Jan Jun Apr Oct th Jul ( mm/day Eto 3,3 3,6 4,9 6,7 8.0 8.0 9.0 8,2 8,1 6,1 4,8 3,5 ) The tomato Crop Coefficient vs. Growth Stage graph shows how the crop coefficient changes according to the Growth Stage (Figure1). Table 2 shows the average Kc values for the various crops during growth stages. In fact, the Kc is also dependent on the climate and, in particular, on the relative humidity and the wind speed. Table 3. Shows the crops stage interval for some vegetable crops. 4 Technical manual for “Fertigation manual: Open-field crops and date palm" Example 1 Estimation of actual crop evapotranspiration( Etc) Calculate the daily tomato Etc and gross depth water applied (dg) during April using drip irrigation system with wetting percentage (WP) of 40% Data input Crop : Tomato Eto: from table 1=6,7 mm/day Kc: from Table2 & Table3 or Figure1=1,15 Irrigation efficiency = 0,86 ECw: salinity of irrigation water (dS/m)=5 dS/m maxECe = maximum soil extract salinity (dS/m) (Table 4 ) =8,4 dS/m Soil wetting percentage(WP) = 40 % Solution Etc = Eto*Kc = 7.71 mm/day Leaching requirement (LR)= Ecw/2ECe= 0.30 0.9*dn dg (1 LR)*Ea 0.9*7.71*0.4 dg 4.9mm 49m3/ ha (1 0.3)*0.81 Table 2. Values of the crop coefficient (Kc) for various crops and growth stages. Crop Kcini Kcmid Kcend Crop height (m) Lettuce 1.00 0.95 0.3 Sweet peppers (bell) 1.05