Understanding Soil Tests: What do all those numbers mean?

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Understanding Soil Tests: What do all those numbers mean?

Right about this time of year farmers are awaiting that little packet in the mail, or that pick-up to drive into their driveway. Whichever way it arrives, through the mail, or from a local consultant, the data is the same. Farmers want to see how their soils are doing so they keep vigil waiting to get their soil report back. Once it arrives they scan the data, then look to the bottom line conclusions and recommendations. Just what do those numbers and graphs mean, and why did they suggest that particular application of a specific mineral or nutrient. Convincing yourself of the need to soil test is just half of the battle. The real work begins in understanding what your soils are telling you once the report arrives via mail, or in the hands of your consultant.

Soil Profile
Properly balanced soils should be made up of these elements to be able to support life and transfer adequate amounts of energy to plants above the soil line.

The Basics
All soil tests, from reputable labs, should give you the break down of N,P,K, Ca, Mg, soil composition and percentage of organic matter. Better tests, from better labs, will indicate not only what elements are present, but also what is available for use by your given crop. According to Mir Seyedbagheri, University of Idaho, “It is the difference between looking at your balance, and your available balance in your checking account. One tells you what you have, the other indicates what may be committed or ‘locked up’ elsewhere.” When you first look at your test, look first at the numbers of these base elements to make sure they are within range for the crop you are trying to grow. If not, you may need to amend your soils. Dennis Stephens, President of Monty’s Plant Food Company commented on the need for careful evaluation of the soil tests. “Soils to be healthy need to follow these basic guidelines – 45% Minerals, 5% Organic Matter, 25% Atmospheric Air, 25% Water. When these are present at these levels then production can be maximized.”

Beyond simple percentages those minerals need to consist of specific elements and micronutrients for the ecosystem within your soil profile to function efficiently.

What To Look For
Soil specialist Paul Leeds indicated that he can tell just by looking at a thorough soil test if a given farm has problems with weed pressure, fungi, or diseases. After putting him to the test, I asked him what it was, specifically, that he was looking for, and how rank and file farmers could begin to train themselves; what he revealed was eye-opening. What follows is a breakdown of what you should look for, and what problems are lurking when elements are out of balance in your soil profile.

Nutrient	Key Ratios	Benefit	Signs of Deficiency
Calcium	7:1 with Mg; 5:1 with K	Standability, drought and freeze tolerance	increased K uptake in plant, diseased crops, increased fungal presence
Magnesium	1:7 with Ca	increased carbon/nitrogen exchange with soil and air, increased sugar production	lower Brix levels, poor soil structure
Phosphorous	1:4 with K	less weed pressure and competition from invasive species	increase in broadleaf weed numbers
Potash	1:5 with Ca; 4:1 with P	adequate calcium uptake, stronger cell walls. better standability during dry-down	increase susceptibility to disease and fungi
Boron		Disease control, Sugar Production/Movement, improved pollination	usually will not show up until fruit set. wheat will display empty socks; corn will not fill to end
Copper		improved disease control especially fungal disease and those related to extreme wet conditions	increased stalk breakage, lodging increased shatter during harvest, inelastic cell walls
Manganese		improved seeding vigor; when used on feed crops it improves breed back; critical for tree nut production	decreased yields especially in soybeans and nut crops
Zinc		better water uptake, drought tolerance	early signs of drought stress

An old saying says “If you don’t where you’re going, you wont know when you’re there.” If you are trying to achieve healthy, sustainable soils you have to know what health looks like. Quality, productive soils must have certain elements in addition to N,P, & K, and all of them must be present in proportion to one another. According to Leeds, for example, if calcium is not in proper proportion to magnesium, “Your soil structure will be out of line. This ratio represents your soil structure, how much exchange capacity you will have, how much water holding capacity you will maintain, and it supports carbon to nitrogen exchange which is imperative for the production of sugars that your plants need for energy.” Similarly, if boron is not present in sufficient quantities then you will notice higher disease pressure, and decreased pollination. Many of the problems that farmers spend millions of dollars on annually to eradicate can be greatly reduced if we bring soil and plant nutrition into balance.

The cost of traditional soil amendments have risen sharply over the past year leaving some farmers choosing between yield and profit. If you arm yourself with the necessary information, test adequately, and analyze the data properly you may find that with some comparatively low cost amendments either applied to the soil or directly to your plants you can maintain or increase your yield and quality, while maintaining profitability. Stephens concluded by saying, “At Monty’s we want to provide a product that works, at low application rates, so that we can truly have an agricultural industry that is profitable and sustainable.”

If you are looking for additional information check with your local county extension agent, extension soil specialist, or contact one of these companies www.midwestlabs.com or www.montysplantfood.com .