 Hi, I'm Eric Barstis, Conservation Agronomist with the Natural Resources Conservation Service. I'm Erin Cordes, SDSU Extension Specialist. Welcome to this IGRO podcast, which is here to explain soil sampling for nutrient management. What we're going to talk about is how to take a composite soil sample using a handheld probe. So why sample in the first place? Soil sampling is a critical part of a comprehensive nutrient management plan that makes most out of your fertilizer. Whether your fertilizer is manure or a commercial fertilizer. What it helps is achieve better yields, reduced production costs, and reduced water pollution. With sampling, what we're trying to do is determine the existing soil fertility levels because those soil fertility levels vary by area, by time, and also by practice, management practices. Also these samples can be required by some different permit programs like a CAFO general permit program. So it is an integral part of a comprehensive nutrient management plan. So you might be wondering, when do I take a sample? Sampling at approximately the same time each year helps get consistent results. You also want a sample in the fall, gives you a longer window to sample, and also gives you time to analyze those results and develop a fertilizer program. Collecting soil samples after the soil temps are 50 degrees or below will reduce the amount of any changes in mineralization in the nitrogen of the soil. And again, before any nitrogen requiring crop, we suggest taking a sample, that'd be corn, small grain, things like that. And every two to four years for immobile nutrients seems to be adequate. Before you go out to take a sample, you want to make sure that you have all the equipment you need. This would consist of your soil sampling probe, probe brush to clean out the probe, two buckets if you're taking deep sample for immobile nutrients, and penetrating oil or lubricant, some sample bags to collect the samples in, and a means to transport yourself across the field, whether using a four-wheeler or pick up, make sure you have adequate equipment like bungee cords to hold or secure the buckets down, things like that. So here's all the material I need to take a good soil sample. I have my sampling buckets, small bucket for zero to six inch. Larger bucket for the six to 24 inch sample. Penetrating oil to keep the probe sampling good. I'll spray that in between each sample, or kind of as needed. A material kind of like WD-40 seems to work well. Sampling bags to put myself samples in, and a pen to identify those samples. When taking deep samples for immobile nutrients, you want to make sure to remember that there's two sample bags will be sent to the lab to equal one representation for that field. When you're planning the route, you can do either a zone sample, grid sample, or composite sample, and you want to capture the variability within that field based on your sampling technique. So if you're doing a composite sample, you want to make sure you're zigzagging across the field in a random pattern. Make sure you avoid the very top part of the hills and the very lowest spots, and make sure you just keep sampling until you get a good representation. Typically takes 15 to 20 cores for an 80-acre field. And when you're collecting that sample, zero to six inches for immobile nutrients like phosphorus potassium, six to 24 inches for mobile nutrients, nitrogen, sulfur, things like that. And in some situations, a deeper sample may be required up to 48 inches for high leaching soils and for some permit requirements. OK, we'll try taking a sample here in this spot and see if we can get a sample taken. I should spray the probe, put a light layer of WD-40 on, front and back. I'm going to try to go down 24 inches. I was very careful to keep the hole exactly there. Didn't let any dirt fall in. So I've got my top six inches. My mark is right here, so I'll put that in one bucket. Six to 24 inches will go in the other bucket. And now my probe isn't 24 inches long. So I need to go down the same spot again to get the rest of my sample. Scrape off that top soil, clean that off. That was just a little bit of dirt there that did fall in to the hole. And I can easily see that from the different color of the soil there. So that will make up the rest of my sample. If I do have any dirt left in here, I will clean it with this cleaning brush and get ready for the next sample. And always remember to complete your soil sample information sheet. This is what the lab needs to know what nutrients to include in the analysis and it helps them to identify the fields and gives your contact information so where they can return the analysis to. And proper handling of the sample would be the last step. Make sure that you either freeze the sample and keep it frozen until sending to the lab or you can air dry the sample at room temperature. Just lay it all out and put a fan on it to air dry it and then collect it back up and send to the lab at that point. We hope that these steps have helped you identify how to collect a good representative sample from your field. Now that you have that sample, what do you do with it? We recommend that you send this sample to the lab on a Monday. This helps reduce the amount of change in that sample from its frozen or its dried state in the mail. If you send it on a Monday, it has better chance of reaching the lab during that week and getting to that analysis stage. Finally, when you do receive your results, make sure you use those analysis results in conjunction with the crop requirements to determine the fertilizer needs. Put this soil analysis and the results to the best use possible. Thanks for participating in our podcast. We hope we provided you with some useful information on how to take a composite soil sample using a handheld probe. For more information, here are some documents that you can refer to at a later time.