Soybean Rolling: Yield Effects

 

Land rolling soybeans has become a common management practice in many areas of South Dakota. The practice originated in Canada and has since spread to Minnesota, the Dakotas, and some areas of the Corn Belt where rocky soils are common.

 

The main reason for using a land roller on soybean fields is to push down rocks and level the soil surface for harvest, in theory reducing the amount of rocks and other debris that can potentially damage a combine header. Roller enthusiasts also promote a faster, easier, and ‘cleaner’ harvest.

 

 

Studies performed in Minnesota and Iowa examined the yield effects when soybean rolling was performed at various growth stages. There was no difference in yield due to growth stage of the soybean plant up until V3 (the 3rd trifoliate). Rolling at the 6th trifoliate caused severe plant damage resulting in a yield loss of nearly 9 bu/acre. The results of these studies confirm earlier research from North Dakota State University, which also noted no significant yield losses due to growth stage up to V3, but documented increased crop injury after the plants are 3-4 inches tall. The results of the Iowa and Minnesota studies are reported in Table 1.

 

Some other studies have shown small increases in yield when rolling is performed at the V1-V3 growth stages, in theory due to increased node production caused by plant stress, but these results are not always statistically significant.

 

Table 1. Average soybean yields across multiple locations in Minnesota and Iowa for various rolling times (DeJong-Hughes et al., UMN, Al-Kaisi et al., ISU).

 

 

 

In low residue situations, land rolling may ‘seal’ the soil surface, which can lead to ponding during rain events. Experience has shown a significant rain event immediately following rolling can lead to crusting which may severely affect germination. Deformed soybean seedlings due to roller-induced crusting are shown in Figure 1. In a 2008 Minnesota study, a hard rain immediately following soybean rolling resulted in a 95% stand reduction (Figure 2).

 

Figure 1. Soybean seedlings at various stages of emergence. Swollen and broken hypocotyls present on some of the seedlings are a symptom growth impairment due to soil crusting.

 

Figure 2. Germination effects of a hard rain on rolled (right) and non-rolled soybeans (left).

 

 

While land rolling in soybean does not seem to provide a direct yield response, it provides ‘peace of mind’ during harvest in rocky soils. It is important to roll soybeans at the V3 growth stage or younger, when plants are still pliable enough to bounce back. If rolling after emergence, roll during the heat of the day when plants are limp, not in the early morning or evening. Keep an eye on weather forecasts and try to avoid rolling prior to emergence if a heavy rain is in the forecast.