LIBRANZA, Alexander Ken 2 BS ABE SOIL SAMPLING and ANALYSISJuly 7, 2012 CRSC 10 SOIL SAMPLING is the process of taking a representative/sample from the field to identify the area in question. Soils are sampled to determine physical conditions, fertility (nutrient) status, and chemical properties that affect their suitability as plant growing media. Through a combination of field and greenhouse research, analytical methods have been developed which provide quantitative estimates of plant-available nutrients. Field research determines the optimum soil test levels for various nutrients for specific soil and crop combinations. Optimum fertilizer practices can be determined by knowing the optimum test level of each nutrient for a specific crop and soil, and by knowing how much fertilizer is required to change soil test values. Soil testing is comprised of four steps: (1) Collection of a representative soil sample, (2) Laboratory analyses of the soil sample, (3) Interpretation of analytical results, and, (4) Management recommendations based on interpreted analytical results. The first and most critical step in soil testing is collecting a soil sample. A soil analysis can only be as good as the sample sent to the laboratory. Therefore, it is vital that the soil sample be representative of the entire field. Two layers of the soils are analyzed: the top soils and the subsoil. Top soil refers to the top layer of soil that has a mix of vegetative matter and soil in it. It is usually a darker color than the deeper subsoil because of its higher organic content. Because of this relative organic richness, it is generally easier to handle than subsoil. It cultivates better, is less sticky or likely to cake. Subsoil is usually lighter in color, stickier, less fertile and more difficult to handle. Generally, the top soil is darker because of the amount of decomposed plant matter in it - and the subsoil is lighter because it is mostly the mineral content: silt, clay, and sand. In the process, we are first introduced to the Do’s and Don’ts of soil sampling. No soil samples from road cuts/ road sides/ landfills A difference in soil topography is very important. (Soil sample from sloping area is different from the soil sample on the flat area) Visual observation on the area. (Through physical appearance of the plants – color of leaves, size of the stems, fruit-bearing – we could easily identify nutrient losses and absent on that certain area in question.) Hidden hunger of the plants (Some plants may appear healthy, but through research and observation, we could easily identify the actual condition of the plant) – this would also help identify the maximum potential of the plant to provide to the farmer. Optimum condition of the soil – not too wet and not too dry In case of rain, Soil samples should be collected at least 3 days after the rain. SMOKING is highly discouraged while taking soil sample since it can affect/ alter the chemical properties of the plants. Testers are required to wear cloves to prevent alteration of the soil properties because of the chemicals that are present in their hands. Using a soil auger, we take soil samples from the field. First is that we have to remove all vegetation from the area in question. In the process, you need to dig 0-6 inches to get a sample of the topsoil, and 6-12 inches for the subsoil. Twenty holes are the minimum number of sampling sites to cover the whole hectare, however, the more samples we collect, the more efficient our sample will become. Holes/ sampling sites are made in zigzag or W- pattern to efficiently represent our area. From those holes, we collect soil samples and place them in clean plastic bags or any clean container free from chemicals that might damage our sample. Soil samples are commonly at least a kilo – 500 grams of topsoil and 500 grams of subsoil. These samples are collected randomly from the different holes made. Samples from different holes are collected and mixed to create one composite soil sample. Then, the collected sample is taken to the laboratory to be air dried in room temperature. Air drying is done by scattered properly in a week or more depending on the need of the soil. Then, the sample will be sieved. Half of the sample will be sent to the laboratories for analysis and the other half will be kept for future purposes or failure in the first sample. SOIL SAMPLING can be done annually but the most common soil sampling is done every 3-5 years because this is the span of time that changes in the soil properties occur. Also, in doing soil sampling, we do not only look at the physical and chemical properties of the soil, we also take into account the history of the area – What were the plants planted there? Was there a shift of crops? Are there any animals inhabiting the area? - These information will give us historical evidence of the area in question. To prevent failure we need to observe the Dos and Don’ts of soil sampling that are stated above. Alterations, changes and failure sample are most commonly due to errors done before, during, and after the process. A vigilant mind is needed on the whole span of the activity. ______________________________ http://wiki.answers.com/Q/What_are_the_differences_between_top_soil_and_sub_soil#i xzz1zvat02bF Soil Sampling and Analysis, J.L. Walworth, University of Arizona, College of Agriculture and Life Sciences, “AZ142.pdf” LEAF SAMPLING and ANALYSIS After examining what the soil has to offer to our plant, we now precede on what nutrients have the plant been taking from the soil or what the soil has been providing to the plant for its growth and development. Leaf analysis provides information about the nutritional status of a crop and can be used to identify nutrient imbalances, deficiencies and toxicities. In applying fertilizers, the best method of determining the kind and amount of fertilizer to apply to fruit trees is by leaf analyses. It effectively measures macro and micronutrients and indicates the need for changes in fertilizer programs. Leaf analyses integrate all the factors that might influence nutrient availability and uptake. It shows the balance between nutrients. We start the sampling by identifying the different leaf number – such as: Leaf #9 – the leaf holding the spith (bungol), biggest inflorescence Leaf #14 – leaf holding the fist-sized coconut Leaf #19 – leaf holding the adult coconut (butong) Secondly, we identify/ learned that coconuts have handedness. Facing the coconut, the direction where the leaf number 14 is pointing, is the handedness of the coconut. The specific coconut that we observed is Left-handed. Sample leaflets are taken from the Leaf #14 since it has the optimum level of leaf nutrients which is neither too old or too young. We gather a minimum of five leaflets from the middle of the leaf #14. Then those leaflets would be detached from the stick (removing them from its midrib), and then again cut and will only make use of the middle of the leaflet. The sample should be composed of 5 leaflets randomly taken from 20 trees in the area in question. The collection would then make up one composite leaf sample. The appropriate time for leaf sampling in the day is between 9am to 2pm. In case of rain, leaf samples should be collected at least 3 days after the rain. In collecting leaf samples, we should always keep it safe from chemicals that might damage our sample. In cleaning the leaf, we need to use tap distilled water to prevent chemical alteration, and changes due to temperature. When we collected enough leaf samples, we send the leaf samples to the laboratory to be oven dried at 80°C for 24 hours. When the samples are ready, we then label it with the following: sample code, area where it is taken, treatments used, leaf rank, other relative information needed, and who prepared the sample. _______________________ http://cottassist.cottoncrc.org.au/NutriLOGIC/ LEAF SAMPLING & ANALYSES, Duncan Weir1 Ian Rochester, Agri-science Queensland, CSIRO. 2009, “Leaf_Sand_A2_pg2011.pdf” QUESTIONS TO PONDER: 1. What is meant by essential elements? Essential elements are those numbers of mineral nutrients that are absolutely essential to plant life. They are essential because a plant deprived of any “one” of these elements would cease to exist. Plants will use essential elements only in proportion to each other, and the element that is in shortest supply—in proportion to the rest—will determine how well the plant uses the other nutrient elements The 'beneficial elements' are those that can compensate for toxic effects of other elements, or may replace mineral nutrients in some other less specific functions such as the maintenance of osmotic pressure. There are 16 nutrient elements required to grow crops. Three essential nutrients—carbon (C), hydrogen (H) and oxygen (O2)—are taken up from atmospheric carbon dioxide and water. The other 13 nutrients are taken up from the soil and are usually grouped as primary nutrients, secondary nutrients and micronutrients. Knowing the nutrients required to grow plants is only one aspect of successful crop production. Optimum yield also requires knowing the rate to apply, the method and time of application, the source of nutrients to use, and how the elements are influenced by soil and climatic conditions. 2. What is meant by microelements? Microelements/ Micronutrients are those nutrients that are demanded only in trace amounts. This includes iron (Fe), manganese (Mn), boron (B), zinc (Zn), copper (Cu), molybdenum (Mo), chloride (Cl), sodium (Na), nickel (Ni), silicon (Si), cobalt (Co) and selenium (Se). The importance of micro-elements in plant nutrition is high and they should not be neglected although they are needed in minor quantities. Any deficiency of a nutrient, no matter how small the amount needed, it will hold back plant development. 3. After a farmer has received the result of soil or leaf analysis, what could be his/her next move? The last step I presented in the soil analysis includes Management recommendations based on interpreted analytical results. The farmer after receiving the result should properly interpret the soil-leaf analysis values, and then develop a fertilizer management program for his/her crops. However, fertilizer programs are crop specific and sometimes dependent on additional soil and climatic properties, and are beyond the scope of this document. With the use of this analysis, farmers could produce better yield and would at least lessen crop failure. _______________________ “cals.arizona.edu/pubs/crops/az1412.pdf,” James L. Walworth, State Soil Specialist, The University of Arizona Cooperative Extension, The University of Arizona, College of Agriculture and Life Sciences, Tucson, Arizona 85721 “MICRO-ELEMENTS in Agriculture,” Practical Hydroponics & Greenhouses . July/August . 2007 “Essential Plant Nutrients: their presence in North Carolina soils and role in plant nutrition,” M. Ray Tucker, Agronomist, NCDA & CS Agronomic Divisions, October 1999.