Extended periods of soggy conditions in late 2018 and early 2019 have caused a myriad of problems for Georgia cattlemen and hay producers. Speakers at the 2019 Georgia Forage Conference offered tips on how to manage drenched forage land.
The conference, held April 4 as a part of the Georgia Cattlemen’s Association Convention & Trade Show, featured presentations on effects of excess water, from nutrient loss to weed pressure.
UGA Agricultural Climatologist Pam Knox suggested that Georgia weather overall could be warmer and wetter than normal through most of the year and recommended producers pay close attention to weather developments in the tropics.
“A lot of the warmer temperatures are going to be night-time temperatures,” Knox said. “That will increase evaporation rates, and if night-time temperature is high and you have animals outside that don’t like the heat, they’re not going to be happy if they can’t cool off at night.”
Reclaim or renovate?
UGA doctoral student Tayler Denman presented a plan for producers to follow to determine whether to perform light maintenance on their pastures or to renovate them entirely. Denman shared the pasture condition scoring system developed by the USDA’s Natural Resources Conservation Service. The NRCS has a worksheet available to help producers decide what their pastures need at www.gfb.ag/NRCSPastureCondWksht.
Scores of 3 and above indicate pasture management is needed, Denman said, outlining three steps: Taking soil samples, managing weeds in the pasture, and fertilizing after the weeds are under control. Scores of 1 or 2 indicate the pasture is too damaged to manage and should be renovated. She said this involves taking soil samples, planning the types of forage to plant and destroying the existing stand with herbicides.
Effects of excess water on soil nutrient content
UGA Extension Forage Agronomist Lisa Baxter reviewed the possible effects of excess water on nutrients in soil – runoff, leaching, volatilization, denitrification and acidic rainfall.
“The consequences of wet soil conditions really depend on where we are in the state,” Baxter said. “If we’re in the coastal plain, we have really sandy soil and low water-holding capacity and we’re going to have a lot of leaching going on. If we get up into the mountains, we have a lot of steep hill banks, that’s where we start getting into runoff.”
Runoff is where flowing water carries away nutrients at or near the top of the soil. Leaching is where excess water moving down through the soil carries nutrients with it. Volatilization is where nutrients are lost to the atmosphere when water triggers their conversion to vapor or gas form. Denitrification is where nitrates are lost to the atmosphere by the same process. These things happen at varying rates depending on the nutrient mobility.
Acidic rainfall isn’t as common in Georgia, though Baxter said if extreme rainfall conditions continue, it can alter the pH balance in the soil, causing it to become acidic over time.
Whether it’s nitrogen or potassium, Baxter recommended rationing fertilizer applications over the course of the season rather than putting it out all at once.
Combating weed pressure
UGA Assistant Professor of Crop & Soil Sciences Nick Basinger discussed how wet conditions contribute to weed concerns in forage land. First, he noted the soil always contains a weed seed bank, a collection of seeds that survived from previous years and is waiting for the right conditions to germinate.
“The ones that make it through are your weed problem,” Basinger said. ‘They’re the problems you’re dealing with.”
He reviewed some key species of weeds that thrive in wet areas, particularly varieties of sedges, foxtail, Japanese stiltgrass and buttercup. Buttercup is especially troublesome in pastures because it is toxic to livestock.
To combat weeds, Basinger recommended maintaining strong stands of desired grasses and to avoid overgrazing.