Wisconsin Dairy Lagoon Trial: 37% More Plant-Available Nitrogen and Higher Manure Fertilizer Value with Pit Puck Tablets

Is cow manure a good fertilizer?

Liquid dairy manure is a real fertilizer, but its value swings widely with how the storage is managed. In this Wisconsin lagoon, the same manure carried 172.4 lbs of plant-available nitrogen per acre before treatment and 237.0 lbs after, at an identical 20,000 gallon rate. Same lagoon, same farm, 64.6 more pounds of nitrogen per acre.

How much nitrogen is in liquid dairy manure?

It depends on the herd, the ration, dilution, and how well the storage is digesting. The useful figure is plant-available nitrogen at your actual application rate, not total nitrogen. This farm measured 11.85 units of nitrogen after treatment, which works out to 237.0 lbs per acre at 20,000 gallons, against 172.4 lbs from the untreated baseline sample.

How do you increase the nutrient value of manure?

Most of the gain comes from getting the storage biologically active so solids break down and the slurry going out the pump is more consistent. Adding a microbial tablet to this lagoon lifted plant-available nitrogen 37% and potassium 20% per acre, without changing the herd, the ration, or the spreading rate.

Why does phosphorus limit manure application rates?

Nutrient management plans generally cap manure by the phosphorus a crop can take up, since excess phosphorus runs off into surface water. Nitrogen is usually the nutrient you want more of, so a high phosphorus concentration forces you to spread thin and cover more acres. Here phosphorus dropped 13.4 lbs per acre while nitrogen climbed, which moves the ratio in the direction a planner wants.

Is a baseline sample the same as a control?

No, and the difference matters. A control is a second, untreated lagoon or parallel stream measured over the same period. A baseline is simply the same lagoon sampled before treatment started. This trial has a baseline, not a control, so changes from settling, temperature and loading over the treatment period cannot be separated from the treatment itself.

Do manure pit additives actually work?

The honest test is whether anything measurable changes. On this farm two things did: the lab numbers on the manure moved substantially, and the physical condition of the lagoon improved, with less sludge, less surface scum, and lower odor during storage and agitation. Results vary with lagoon size, loading, and temperature.

How do you reduce sludge and crust in a manure lagoon?

Sludge and crust are undigested solids, so the fix is biological: give the storage enough of the right bacteria to keep breaking those solids down instead of letting them settle and mat. This lagoon carried noticeably less sludge and scum after treatment, which is what makes agitation and pump-out faster.

How do you apply a manure pit tablet?

You drop it in. The tablets sink and dissolve on their own, delivering bacteria straight into the manure with no mixing, no dosing equipment, and no change to your handling routine. That is the practical reason producers use the tablet format instead of a liquid on pits and lagoons.

How often should you test manure before spreading?

Test often enough that your spreading plan reflects what is actually in the storage, which for most operations means at least annually and again after any change in management. This trial is a good illustration of why: the same lagoon produced materially different nitrogen, potassium, and phosphorus numbers over the treatment period.