CATCH THE BUZZ – Improving Pollinator Buffer Establishment Faces Weeds, Seed Size and Germination Issues.

Panorama of pollinator establishment plots with cool season cover (wheat on left, oats on right)

It can be difficult to establish pollinator habitats via various NRCS conservation practices (e.g. conservation cover, contour buffer strips, field border, filter strip).  The most significant challenge appears to be seedbed preparation and subsequent planting.  The most frequent challenge with the seedbed is the weed seed bank.  Weeds often germinate and grow faster than the desired plant species and challenge the early establishment of those plants.  Additionally, plant mixes that benefit pollinators often contain seeds of widely varying size and shape.  Thus, if the plant mix is planted using only one planting method (e.g. drill, broadcast, etc.), then certain species/types will benefit, while others suffer.  The Norman A. Berg National Plant Materials Center (MDPMC) pollinator buffer establishment project aims to address seedbed preparation and planting method to identify methods to improve establishment of a diverse pollinator habitat. 

In order to address the weed seed bank effect on pollinator plant establishment from seed, we plan to try a number of different techniques to suppress or over-express weed seed pressure.  One treatment will be continuous high seed rate cover cropping to out-compete weeds for approximately one calendar year.  We plan to plant cover crops with known weed suppression characteristics (e.g. cereal rye, sorghum sudangrass).  Another technique for weed suppression will be frequent pesticide application along with light tillage.  Other techniques will be high tillage and solarization.  These techniques will be compared against a control, which will be planting a single standard rate cool season cover which is often specified in conservation standards.

In order to address pollinator plant seed shape effects on plant establishment, we plan to trial various planting methods, like broadcasting, no-till drilling, and dormant seeding.  These treatments will be applied to the standard mesic mix used in Maryland, as well as applied to each individual species within that mix.  We hope the comparison of establishment of individual species against the mix will give a better picture of which species benefit from each planting method (e.g. Do smaller lighter seeds benefit from shallower planting depths and do larger heavier seeds benefit from deeper seed-soil contact?)

The aforementioned seedbed and planting method treatments will be conducted via replicated study at the MDPMC.  Staff are also collaborating with the MD State Biologist on a larger project on the Eastern Shore of MD (on land owned by the Nature Conservancy) to investigate similar treatments. 

Data will be collected at each site on germination, survival, and rate of establishment as measured by mature plants after establishment.  The data from individual species will be compared statistically to the mix to gain some understanding of the role that competition and/or synergy that may occur within the mix. We hope to have preliminary results in the fall of 2018 and a more robust suite of data in 2019.