Giles County, Tennessee
Fourth-generation farmer Jason Birdsong currently farms corn, wheat, and soybeans on a 750-acre operation. He works closely with the local NRCS, Giles County Soil Conservation District, and his local University of Tennessee Extension Service.
Jason has conducted experiments with his local Extension Service on his farm and is enthusiastic about finding and sharing best management practices. So far, he’s found that his soybeans yielded 3.5 bushels more per acre following a five-way cover crop mix compared to using cereal rye alone. In another experiment, Jason used an inoculant for soybeans on his bottom land soils and found a 3-bushel per acre increase. On his hill ground, he conducted the same experiment and showed only a 1/2-bushel increase per acre after using the inoculant.
He formerly applied nutrients based on general removal rates from grains, but now applies only what is needed based on 2-acre soil grid sampling. Jason says he has saved thousands of dollars by switching to variable rate application.
Jason said that his family began experimenting with no-till in the 1970s. With the challenges of getting a good stand, and no commercial herbicides to control weeds, they practiced rotational tillage. In 2010, with better herbicides and technology, he was able to start using no-till full-time and experimenting with cover crops.
He began using wheat as a cover crop in 2010 and used it again in 2011. In 2012, he changed to cereal rye and tillage radishes. He began to see changes in his soil, especially around the planting zone at 2″ in depth: the soil structure was better, and he could achieve a stand with less down pressure on his planter. He said that since 2012, he could back off on any down pressure. He also pulled off the spike wheels. He uses a seed firmer and row cleaners with little or no pressure. Row cleaners are only used when planting double cropped soybeans after wheat.
In 2013, he added wheat with cereal rye and tillage radishes. In 2014, he quit using wheat as a cover crop due to it being a host for pests when rotating back to wheat for grain. He used only cereal rye and tillage radishes. In 2015, he went with a multi-species mix of black oats, crimson clover, purple top turnips, cereal rye, sunn hemp, and tillage radishes. In fall 2016, he planted the same mix with the exception of substituting kale for turnips. He also dropped cereal rye from the mix.
Adding crimson clover to his mix established a symbiotic relationship between bacteria and legumes where nitrogen in the atmosphere is being fixed in the soil. Adding a brassica, such as a turnip or kale, has provided a tap-root for loosening the soil and bringing up nutrients from the subsoil.
Sunn hemp is a warm season cover crop where the rest of the mix are cool season. By planting a warm season cover crop in early September, one receives aggressive growth in early fall. Sunn hemp is also a legume, so nodulation occurs in fall before winter kill. Nitrogen is taken up by the other species and cycled to the following growing season.
Jason saw a bump in yields the first year using a cover crop, but also an imbalance of nitrogen. The second year he saw a slight decrease in yields. Since year three, he has seen steady increases in yield and maintains a good carbon to nitrogen ratio in his cover crop mixes. Usually a 28 to 30:1 ratio is sufficient when providing a mixture of cover crops. Farmers can contact their local NRCS or conservation district office to develop a mixture with proper carbon to nitrogen ratio.
Jason has seen a number of benefits from using no-till and cover crops:
- Higher soil organic matter levels (3.7% SOM in 2014 to 5.4% SOM in 2017);
- Fewer lime applications needed;
- Better water infiltration;
- Better drainage;
- Better structure – more crumbly with less compaction;
- Less weed pressure from palmer pigweed and mares tail;
- Savings on foliar fungicide applications;
- Better functioning tiles; and
- More stable yields.