Planting Green Effects on Corn and Soybean Production

Abstract

No‐till farmers who want more from their cover crops (CCs) are delaying CC termination until the main crop is planted. Delaying termination can help dry wet soils and reduce erosion. This process is referred to as planting green (PG). We hypothesized that PG would (i) dry soil at main crop planting, but conserve soil moisture later in the growing season; (ii) reduce soil temperature; (iii) reduce slug damage on main crops; and (iv) not reduce main crop yield. This experiment was conducted in Pennsylvania between 2015 and 2017 to compare two CC termination dates: preplant killed (PK) and planting green (PG) in corn (Zea mays L.) and soybean [Glycine max (L.) Merr.]. Planting green increased CC biomass an average of 94% and 94 to 181% compared to PK preceding corn and soybean, respectively. Soil was 7 to 24% drier and 0.9°C cooler at corn planting, and 8% drier and 0.7 to 2.4°C cooler at soybean planting in PG compared to PK. Slug damage was not different, lower, or higher in PG corn, and not different or lower in PG soybean compared to PK. Corn yield was reduced and not impacted by PG in higher and lower yielding environments, respectively. Soybean yield was stable across locations, and not affected by cover crop termination date. We concluded that corn was more vulnerable to yield losses from conditions created by PG than soybean; therefore, growers who desire potential benefits and lower risk from PG should first consider soybean. Core Ideas Planting green refers to planting the main crop into a living cover crop. Planting green increased cover crop biomass by 94% in corn and by 94 to 181% in soybean. Planting green dried the soil at main crop planting. Planting green cooled soil 0.7 to 2.4°C at planting. Soybean yield was not influenced by planting green; corn yield was reduced.

Cover crop impacts on soil physical properties: A review

“…For instance, late‐terminated CCs or growing CCs for extended periods produce more biomass and exert greater changes in soil temperature compared with early‐terminated CCs with low biomass production. Reed, Karsten, Curran, Tooker, and Duiker (2019) found that soils under CCs terminated 1–3 wk before main crop (corn or soybean) planting were 0.7–2.4 °C warmer compared with soils under CCs terminated about 5 d after main crop planting due to more biomass produced under late CC termination. Also, CC impact on soil temperature can be greater earlier in the main crop growing season than later because CC residues decompose with time.…”

Effect of Wheat Cover Crop and Split Nitrogen Application on Corn Yield and Nitrogen Use Efficiency

“…Therefore, planting winter cereal cover crops has been encouraged to effectively reduce nitrate-N in the tile drainage. Planting a winter cereal cover crop before corn could decrease corn yield as a result of reduced N availability in spring due to N immobilization caused by high C:N ratio of cover crop residue [12,13] or soil moisture depletion by the winter cereal early in the spring [14]. There have been studies on cover crop N release potentially happening simultaneously with cash crop N demand, but results have shown a decrease in cash crop N uptake [15][16][17].…”

Is allelopathy from winter cover crops affecting row crops?

“…Dicot weed species were more affected by BX compounds from winter cereals than were monocots (La Hovary et al., 2016), but whether this is true for row crops is not clear. In fact, soybean growth and yields were less affected by preceding cereal rye than corn in several studies; however, allelopathic activity was not measured so it is not clear if allelopathy contributed to these effects (Pantoja et al., 2015; Reed et al., 2019). Brassicas’ potential for allelopathic weed control was demonstrated in a recent review (Rehman et al., 2019).…”

“…Another option may be to plant the row crop into the living CC and terminate it once the row crop emerges, past its sensitive period of germination. While planting green (planting into a living CC) is becoming more common, reduced corn populations and yields were reported in a Pennsylvania study where cereal rye was terminated within 5 d of corn planting (Reed et al., 2019). More research on this planting method is necessary to investigate how it affects germination and early growth of the row crop.…”

“…Innovations in CC management could affect their allelopathic impact on row crops. For example, some farmers manage CC to produce high amounts of biomass for weed suppression (Mirsky et al., 2013), interseed CC into row crops at early vegetative stages (Noland et al., 2018), or plant row crops into CC stands before CC termination (“planting green”) (Reed, Karsten, Curran, Tooker, & Duiker, 2019). With the increase in CC acreage and management options, it is essential to identify what role allelopathic compounds from CC may play in row crop yield reductions.…”