Need for Soil Testing? By Drew Mosburg Soil

Why should we test our soil? Identify nutrient needs for specific cropsIdentify nutrient needs for specific crops To keep the soil in the best condition for growing certain cropsTo keep the soil in the best condition for growing certain crops To save money by not over-applying fertilizersTo save money by not over-applying fertilizers Try to decrease variability of mobile soil nutrients such as nitrogenTry to decrease variability of mobile soil nutrients such as nitrogen To make the most profit from our cropsTo make the most profit from our crops

Differences in Nitrogen in the soil

Nitrogen mineralization 2-5% of soil organic nitrogen is mineralized each year2-5% of soil organic nitrogen is mineralized each year A soil contains.2% Organic NA soil contains.2% Organic N So, anywhere from 20 to 40 lbs. of N are mineralized per year in the soil. More likely it is closer to 20So, anywhere from 20 to 40 lbs. of N are mineralized per year in the soil. More likely it is closer to 20

Wasted money A farmer that applies 100 lbs. of N as urea every year will spend roughly $26 per acre at $240/ton of urea plus application costA farmer that applies 100 lbs. of N as urea every year will spend roughly $26 per acre at $240/ton of urea plus application cost According to long term test done at the Lahoma Research Station, the average yield over 30 years for plots with no N is 25.3 bu/acAccording to long term test done at the Lahoma Research Station, the average yield over 30 years for plots with no N is 25.3 bu/ac Average yield for 100 lbs. of applied N is 41.3 bu/ac at the Lahoma Research StationAverage yield for 100 lbs. of applied N is 41.3 bu/ac at the Lahoma Research Station That is a difference of 16 bu/ac/yrThat is a difference of 16 bu/ac/yr

Continued 16 bushels of wheat takes approximately 32 lbs. of N to be produced16 bushels of wheat takes approximately 32 lbs. of N to be produced Of that 100 lbs. applied, approximately only 33% will be used. So, farmers are over applying 67 lbs. on N per year. That is $17.42/ac/yr. Granted some of the N will carry over to next year, they will apply 100 lbs. of N next year and continue the cycleOf that 100 lbs. applied, approximately only 33% will be used. So, farmers are over applying 67 lbs. on N per year. That is $17.42/ac/yr. Granted some of the N will carry over to next year, they will apply 100 lbs. of N next year and continue the cycle This is where soil testing comes into placeThis is where soil testing comes into place

Advantages of soil testing You can find out how much nitrogen is in your soil for $10You can find out how much nitrogen is in your soil for $10 You can use that information to apply N accordinglyYou can use that information to apply N accordingly

Disadvantages of soil testing Erroneous readingsErroneous readings –results of bad soil sampling using a shovel from one spot to represent the whole fieldusing a shovel from one spot to represent the whole field if a composite sample is not used, you have a lesser chance of getting a field averageif a composite sample is not used, you have a lesser chance of getting a field average

Best reason to soil test is that it gives us something to do so we can put dinner on the table.

Use of VRT Exactly the amount that is needed is appliedExactly the amount that is needed is applied You don’t have to go get the soil sample and then send it off and wait for the resultsYou don’t have to go get the soil sample and then send it off and wait for the results More farmer and environmental friendlyMore farmer and environmental friendly

Conclusion In years past, the only way of knowing the amount of nutrients in your soil was to test it every year. This takes time that could be spent doing something else. Today, thanks to research at universities, we have the technology to estimate the amount of nitrogen in the soil and apply accordingly to the yield goal and by doing this, we greatly increase NUE which saves the farmer money and decreases the risk of environmental pollution.

Any Questions?