Grazing Bites by Victor Shelton, Retired NRCS Agronomist/Grazing Specialist Spring is around the corner, I hope. In some areas, early February arrived with heavy snow. In others, it was mostly cold, dry and windy. Regardless of how it showed up, many were simply glad to see grass again once the white melted away – if it was green or brown didn’t matter much. An older relative of mine used to say that if there was snow still hanging around, it was just waiting for more to come. Whether that proves true or not, March reminds us that winter rarely leaves quietly. Each season is different, and so far this one appears to be leaning drier in several areas. As days lengthen and soil temperatures begin inching upward, cool season forages slowly wake from dormancy. Soil temperatures in the upper 30s and 40s can initiate growth, and once we consistently approach 50 degrees, growth accelerates. But seeing green does not mean it is time to graze. March is not normally a part of the grazing season, even if the livestock think otherwise. The only reasonable exception is true stockpiled forage left intentionally from last fall, and only if soil conditions are firm enough to prevent damage. That stockpile was built with purpose, adequate nitrogen and sufficient residual to protect crowns and soil. New spring growth is different. Those first leaves are powered primarily by stored root reserves. Grazing at this stage removes the very solar panels the plant needs to rebuild energy and extend its root system. If moisture becomes limiting later, shallow roots will show stress quickly. Protecting early leaf area is not just about maximizing yield – it is about building resilience. March is also prime time for frost-seeding clover if it has not already been done. Freeze-thaw cycles provide natural seed-to-soil contact for small, smooth seeds like clover. Maintaining legumes in the stand improves forage quality and reduces reliance on commercial nitrogen. A healthy legume component – often 30-to-40 percent of the standby dry weight – contributes biological nitrogen fixation and strengthens overall system resilience. Even where clover is already present, frost-seeding can help maintain adequate levels, particularly with species such as red clover that tend to thin after a few years. If that same species has been growing and nodulating in the field, the proper rhizobium bacteria are likely present. Still, inoculating seed is inexpensive insurance. Without effective nodulation, legumes cannot fully fix atmospheric nitrogen, and the small added cost can protect a much larger return. As spring approaches, it is also time to think ahead nutritionally – not just for the forage, but for the livestock. High-magnesium mineral supplementation should begin before cattle are turned onto rapidly growing cool-season pasture. Grass tetany (hypomagnesemia) is most likely to happen during early spring when forages are lush, rapidly growing, high in potassium and nitrogen, and relatively low in available magnesium. Cool, cloudy weather and stress can increase risk. Lactating cows, especially older cows nursing young calves, are particularly susceptible. Lush, immature forage moves rapidly through the rumen and can reduce effective magnesium availability and absorption. Providing a free-choice, high-magnesium mineral two to four weeks prior to turnout helps build magnesium status before risk increases. Waiting until symptoms appear is often too late. Prevention is far easier than treatment. Grass tetany usually isn’t just about low magnesium. More often, it is about an imbalance – too much potassium in relation to magnesium. When soils are high in potassium – especially following heavy potash applications – plants can take up excess potassium, which can interfere with magnesium availability and absorption in the animal. One practical way to assess potential risk is to look at the ratio of soil test potassium to magnesium. For example, a soil test showing 210 pounds of potassium per acre and 160 pounds of magnesium per acre gives a ratio of 1.3 (210 ÷ 160 = 1.3). When that ratio climbs much above about “1,” particularly on lower Cation Exchange Capacity (CEC) soils, tetany risk is elevated – especially during lush spring growth and in lactating cows. That is also why potash applications on pasture must be managed carefully. Even if soil tests show you have fallen behind and more potassium is needed, it is usually best not to apply more than about 120 pounds of Potassium Oxide (K₂O) (200# of 0-0-60) in a single application on grazing ground. Large single applications can temporarily elevate forage potassium levels, increase tetany risk in cattle, and encourage “luxury consumption,” where plants take up more potassium than they actually require. On lower CEC soils especially, splitting larger needs into two applications is often safer and more efficient. Regardless of soil fertility levels, feeding a high-magnesium mineral to cattle ahead of and during early spring grazing remains cheap insurance. During higher-risk periods, moving from a standard 1-2 percent magnesium mineral to one containing about 12-15 percent magnesium provides a little extra cushion when cows are grazing lush, high-potassium grass. Once we’re past that early flush of growth, we can usually ease back to a normal maintenance mineral. If the season trends wetter than normal, patience will prevent mud damage. If it trends drier than normal, patience will protect root depth, cover and moisture reserves. Either way, disciplined management now sets the stage for what follows. Delay grazing until the forage is truly ready and soils are firm. Prepare livestock nutritionally before turnout. When grazing season does arrive, fields that carried adequate cover through winter will respond faster and more uniformly than those grazed tight last fall. Root reserves, soil protection and moisture retention are all influenced by how much leaf area and residue were left behind. That investment in cover will show up later in the season – especially if conditions turn dry. It is not about maximizing a single grazing event but about optimizing the entire grazing season. Keep on grazing! Reminders & Opportunities Southern Indiana Grazing Conference – March 13, 2026, Shiloh Community Building, Odon, Ind. – Peter Byck, Greg Halich, Barry Fisher and Peter Ballerstedt are speakers. For more information call 812-254-4780 Ext 3 or register at https://sigc2026.eventbrite.com Indiana Forage Council Annual Meeting – March 12, 2026, Gasthof Restaurant, Montgomery, Ind. – 4 p.m. ET (call 812-254-4780 Ext 3 to register)
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