Fertilizer Trial

The first year of a five year comparison between the uses of commercial fertilizer, no fertilizer, and a microbial additive on an existing alfalfa/grass hay stand.

In the late winter of 2012 the management team at Ruby Habitat Foundation found itself putting together the annual plan of operations for the coming year. When it came time to budget for fertilizer on the agricultural fields on the Woodson Ranch we once again wondered if it made financial sense to make the investment in commercial fertilizer. An existing project, the soil health study, has been showing results that would suggest that commercial fertilizer may not always pay when looking at the net income per acre. The cost of fertilizer has never been higher and it is one of the most substantial costs in any farm/ranch budget. The question is: With the application of fertilizer, does the increase in production offset the cost of the fertilizer and the associated application costs? In addition, are their other ways to maintain or increase yields without the use of traditional commercial fertilizers?

As you will read elsewhere in this report, we are currently in the middle of a five year study on soil health in partnership with the local office of the Natural Resource Conservation Service (NRCS). In that trial, we have placed a strong emphasis on building soil health by conducting such practices as no-till drilling, leaving crop residue, and planting soil health cover crops or cocktails. Through that trial we have become aware of products that claim to lessen a crops dependence on fertilizer by feeding or supplementing the soil microbes. The product we chose to use for our fertilizer trial claims that by using their product a producer can expect the following:

  • Decreased input costs by reducing the amount of commercial fertilizer needed.
  • Improved water efficiency and moisture holding capacity resulting in decreased watering needs.
  • Increased nutritional benefits from plants and forages.
  • Improved animal performance when consuming resulting forages.
  • Healthier, hardier plants more resistant to environmental stresses like transplant, extreme temperatures, and drought.
  • Improved soil fertility and tilth.
  • Increased absorption of fertilizer inputs by plants
  • Balanced soil pH thereby making nutrients more available to the plants.

To conduct our trial, we selected a 15 acre field that is currently planted to a grass/alfalfa hay mix. It has one soil type and is uniformly irrigated by a wheel line sprinkler system. We broke the field down into three, five acre plots; one each for the commercial fertilizer, the microbial product and the no fertilizer control. We then applied the recommended rates of both the commercial fertilizer and the microbial product. The site was regularly irrigated throughout the growing season. Our intent was to compare the inputs, yields, and net revenue from each plot. On July 2nd NRCS and ranch staff took clippings from each plot. Samples were taken randomly using 2 sq. ft frames. After air drying the samples, they were weighed to determine total biomass. The results were as follows:

Plot Av. Grams Lbs./acre Ton’s / acre Product $/acre
Microbial 140 6751 3.4 $20.00
Fertilizer 131 6290 3.1 $46.42
Control 120 5762 2.9 $00.00

After the first year, our results suggest that the microbial product increased our yield from the control plot by .5 ton/acre. The initial results also show that the fertilized plot had a .2 ton/acre increase over the control. Over the next four years we will replicate this process and monitor our results, publishing them in our annual reports.

There is an increasing interest in microbial products and their success locally. It is our intent to provide an unbiased study for the benefit of local producers and help determine if indeed microbial products will lessen the dependence on commercial fertilizer when applied to a hay stand.