Soybeans grow well under various tillage systems, including conventional, minimum tillage, and no-till. Approximately two-thirds of the soybean crop in Ontario is grown with minimal tillage and no-till systems. Proper management of the tillage system is as important as the system selected. Field experience has demonstrated similar yields between tillage systems, although a global meta-analysis of no-till relative to conventional tillage yields did show slightly lower yields in no-till (5.1% across 50 crops and 6005 paired observations in 678 studies)*. However, since no-till production costs are lower this small yield difference often means that no-till is more profitable.
Soybeans are particularly well suited to no-till and perform better than other crops such as corn in no-till. Ontario tillage research has found that no-till soybean yields were similar to the fall moldboard plow and other tillage systems in all row widths except for single 76-cm (30-in.) rows, see Table 1, Soybean Yield Response Under Various Tillage Systems. Since early season no-till growth is slower compared to conventional tillage, wide rows are not ideal for no-till, especially when planted late. Where single 76-cm (30-in.) rows were used, moldboard plowing produced the highest yields. When soybeans were planted in twin rows, yields improved over 76-cm (30-in.) rows and were equal to narrower rows. Field experience has shown that twin rows are well suited for a zone till (strip tillage) systems and will yield the same as narrow rows. In this study, zone tillage showed no significant yield improvement over no-till.
Table 1. Soybean Yield Under Various Tillage Systems
| A difference of less than 0.16 t/ha (2.4 bu/acre) is statistically insignificant. | |||||
| LEGEND: – = no data available | |||||
| Row Width | |||||
| Tillage1 | Single 76 cm (30 in.) | Twin 76 cm (30 in.) | 56 cm (22.5 in.) | 38 cm (15 in.) | 19 cm (7.5 in.) |
| No-till | 2.72 t/ha (40.4 bu/acre) | 3.04 t/ha (45.3 bu/acre) | 2.93 t/ha (43.6 bu/acre) | 3.06 t/ha (45.5 bu/acre) | 3.06 t/ha (45.5 bu/acre) |
| Fall moldboard | 2.94 t/ha (43.8 bu/acre) | 3.02 t/ha (44.9 bu/acre) | 2.93 t/ha (43.6 bu/acre) | 3.12 t/ha (46.4 bu/acre) | 3.2 t/ha (47.7 bu/acre) |
| Fall zone-till | 2.78 t/ha (41.3 bu/acre) | 2.93 t/ha (43.6 bu/acre) | – | – | – |
| Spring zone-till | 2.71 t/ha (40.3 bu/acre) | 3.02 t/ha (45.0 bu/acre) | – | – | – |
| 1Trials were conducted on clay loam, silty-clay loam, silt loam and Guelph loam soil types. 2Spring zone-tillage conducted approximately 1 day prior to planting. | |||||
No-till soybean plants are often shorter when compared to a tilled fields and may have reduced plant stands. This could explain why some Ontario tillage research trials have shown a small yield gain (about 0.13 t/ha, 2 bu/acre) to vertical tillage compared to no-till, see table 2, Soybean Yield Response to Spring Minimal Tillage. This yield difference can be more significant in poor growing seasons or unique situations. There may be an immediate yield response to tillage in fields with a poor crop rotation compared to a crop rotation with fewer soybeans. However, over the long term, in crop rotations with many years of soybeans, no-till soybeans will yield slightly higher than tilled soybeans, see the factsheet titled, Crop Rotations. This higher no-till yield is likely due to the decreased soil structure, organic matter, and overall soil health associated with long term tillage. In poorly drained fields, heavy soil types or compacted soils, soybeans are more likely to benefit from some form of tillage. Fields with high crop residue can also suffer in a no-till system. Managing the previous crop residue is an important step in successful no-till soybean production, see factsheet, Managing Corn Residue. No-till can yield higher than conventional tillage, especially in dry years or on lighter soil types. There is less white mould disease pressure in no-till fields. Avoid tillage along highly erodible knolls and slopes. The benefits of reduced soil erosion far outweigh any potential yield increases to tillage. Ontario research has not found a yield benefit to aggressive or deep tillage for soybeans.
For successful no-till production, minimize compaction, manage residue, and plant only when soil conditions are fit. Choosing a soybean variety that is suited for no-till is also important. These varieties are relatively tall, bushy, and have excellent vigour. Adopting no-till can be more challenging on heavy textured soil types (clay, silty clay loam, or silty clay) than on light textured soil. Adopting a no till system is also more challenging in a cooler growing region. Heavy corn residue from the previous crop can be challenging for no-till drills to penetrate, leading to reduced plant stands. A slightly higher seeding rate (10%) in a no-till system can be used to overcome some of the plant stand reductions associated with no-till. Slug feeding can be a serious early season problem in no-till, especially in wet years.
Planting of no-till fields is usually done a few days later than in conventionally tilled fields due to wetter and cooler soil conditions. This problem can be mitigated with springtime vertical tillage (shallow minimal tillage leaving much of the crop residue on the surface). Vertical tillage with a one-pass coulter implement has shown a small yield benefit over straight no-till, see Figure 1. Ideally, at least 30% of the residue should be left on the soil surface to minimize soil erosion.
Figure 1. A vertical tillage implement used to cut and bury corn residue before a soybean crop.
Coulters attached to a drill operated at the time of seeding have also demonstrated a marginal benefit if run at a depth of 9 cm (3.5 in.). Coulters operated at a depth of 3.8 cm (1.5 in.) showed no yield gain in the research summarized in Table 2, Soybean Yield Response to Spring Minimal Tillage. It is important to wait for subsurface conditions to be dry enough to avoid compaction regardless of the tillage implement used. Soybeans are highly sensitive to soil compaction. Even though the soil’s top 5 cm (2 in.) may be dry enough to conduct vertical tillage, subsurface compaction may still occur if subsurface conditions are too wet, resulting in lower yields.
Table 2. Soybean Yield Response to Spring Minimal Tillage
| LEGEND: — = no data available | ||
| Treatment1 | Depth | Average Yield2 |
| No-till drill2 | — | 3.03 t/ha (45.1 bu/acre) |
| No-till drill with coulters2 | 3.8-cm (1.5 in.) | 3.05 t/ha (45.4 bu/acre) |
| No-till drill with coulters2 | 9-cm (3.5 in.) | 3.09 t/ha (46.0 bu/acre) |
| Vertical tillage -operated 1–3 days prior to seeding | 9-cm (3.5 in.) | 3.1 t/ha (46.9 bu/acre) |
| Least Significant Difference (P = 0.05) = 0.4 bu | ||
| 1 Values based on 40 trials seeded with a JD 1560 no-till drill. Coulters run at seeding time in the row (2-cm or 0.75-in. wide coulters) were added to the JD drill on a separate tool bar. Vertical tillage implements operated 1–3 days before seeding at a depth of 9 cm (4.5 cm or 1.75 in. wide coulters). 2 No statistical difference between no-till drill and no-till drill with coulters. Source: Bohner | ||
References
*Cameron M. Pittelkow a, Bruce A. Linquist a, Mark E. Lundy a, Xinqiang Liang b, Kees Jan van Groenigen c, Juhwan Lee d, Natasja van Gestel c, Johan Six d, Rodney T. Venterea e f, Chris van Kessel a When does no-till yield more? A global meta-analysis. Field Crops Research, Volume 183, November 2015, pages 156-168