— Livestock excretion rate errors – The model uses incorrect data in its assumptions for excretion rates of nitrogen and phosphorus in livestock manures. The model does not give credit for the use of phytase, an additive to poultry feed that has been used in Maryland to reduce the amount of phosphorus excreted by chickens. Researchers have concluded that the manure loads per animal are too high in the model. Modelers refuse to correct the inaccurate data.
Irrigation management ignored – The model considers every acre of farmland to be managed as dry land. We know that irrigated crops take up more nutrients and give higher yields. In fact, Maryland has 92,000 acres of cropland under irrigation. The corn yield on an irrigated field is 160 bushels per acre – much higher than the 109 bushels assumed in the model.
No credit for innovative practices – EPA modelers say they will give no credit for practices like manure injection, heavy use pads, vegetative environmental buffers and phosphorus incorporation for poultry litter. These practices were used in state calculations for how agriculture was going to meet its goals in the Phase I WIP. If EPA intends to provide no credit for these practices we are setting ourselves up for failure before we even start.
The unwillingness of EPA and modelers to correct the data and the formulas in the model will result in a major waste of local money as counties strive to reach the wrong goals. EPA has said the model is locked in until at least 2017. That’s six years of working towards the wrong goals. That’s only three years from the date by which Maryland has decided to achieve the entire TMDL reduction.
The recent USDA CEAP report (Conservation Effects Assessment Project released in March) has very different conclusions about what is actually happening on farms in the watershed. The CEAP report finds that nearly all acres planted to crops in the Bay region have some kind of voluntary conservation practice in place. The CEAP report shows a different picture than the EPA computer model. EPA’s plan assumes that only 50 percent of the crop acres in the bay region are under conservation tillage. EPA also underestimates the total amount of cropland in the region, relative to USDA’s analysis. These and other discrepancies have raised questions about whether EPA is targeting the real cause of the bay’s water quality challenges.