Soybean pod shatter can happen when plants undergo drought stress during pod development and then receive a late rain.
In general, a loss of four seeds per square foot equals one bushel per acre.1
Fields should be monitored and harvested according to moisture content and combine settings should be adjusted accordingly.
Pod shatter can be caused by a variety of issues but the most common is drought stress. This issue seems to be more common in earlier maturity soybean products. Drought conditions during pod development can result in weak pod structure. When pods rehydrate after they have dried, they may open more easily. Soybean plants that mature prior to late rains would not have added any more weight. Instead, the seeds may have swelled, causing pods to shatter.
Late season spider mite infestations can also lead to premature senescence and increased pod shattering during harvest. Likewise, an early season hail event may leave twisted and empty pods at harvest.
Pre-harvest soybean pod shatter can significantly affect yield potential, especially if it begins while plants are still green. In general, a loss of four seeds per square foot equals one bushel per acre.1 Differences in soybean products may play a role in the tolerance a plant has to shattering. Select a variety of products with relative maturities (RM) that vary by three days for every week of harvest time required for your operation. Therefore, if soybean harvest takes two weeks, it is recommended to plant three or four different maturities that vary collectively in maturity by six days or more. Preventing over-mature pods is a key way to reduce pod shatter.
Fields should be monitored and harvested according to moisture content and combine settings should be adjusted accordingly. Soybean pod shatter loss can increase when green stem syndrome occurs as well. Waiting for a frost or stems to dry down to counter green stem syndrome may increase the risk of yield loss from pods shattering in the field during harvest. Consider harvesting fields when moisture is still at 13% moisture or higher to help reduce the amount of pod shatter.
Slowing down harvest speed can reduce shatter and stubble losses. At high speeds, soybean pods can be stripped from the stem, shatter, and drop to the ground. Always refer to the manufacturer’s manual before performing any maintenance and to confirm the correct settings are being used to minimize harvest losses. Utilizing a belt draper head may also help capture more soybeans than a traditional auger system.
1 Lindsey, L. 2012. Watch out for shattering soybeans. The Ohio State University. Ohio’s Country Journal. http://ocj.com/2012/10/watch-out-for-shattering-soybeans/.
2 Hanna, M. 2012. Combine settings for drought. Integrated Crop Management News. Iowa State University. www.extension.iastate.edu.
3 Soybean shatter discussion. 2013. Technology Development and Agronomy. http://www.channel.com/Agronomics/Pages/Soybean-ShatterDiscussion.aspx.
4 Conley, S. 2012. Drought-induced shatter of pre-harvest soybeans. University of Wisconsin. http://ipcm.wisc.edu/blog/2012/09/drought-induced-shatter/.
5 Schapaugh, W.T. 1997. Selection of soybean varieties. Soybean Production Handbook. C-449. Kansas State University. http://www.harper.k-state.edu/.
6 Hellevang, K. 2013. Soybean maturity, moisture variations may pose problems. North Dakota State University. www.ag.ndsu.edu/.