The topic was geology and agriculture, diverse land formations in various areas of a region contributing to both the growing season and how land is managed for farming. Here in Chester County, we have the second best soil in the world; Alfisols. Mollisols are the best soils in the country, found in the midwest in prairie soils and in the California central valley. You can find descriptions of soil orders and soil taxonomy maps here.
The best soils are loam, and structure is important. The pore space needs to be 50% with 5% organic matter, 45% mineral matter. Clay soils hold nutrients and water, but are often difficult to grow in because of their compacting nature. Loam is equal parts sand, silt and clay.
Dr. Welch called our region 'Rain-sylvania' because our average monthly rainfall is a healthy 2-3 inches. We have few challenges in terms of drought and rarely need to irrigate. Overall for global precipitation variability, PA comes in low, at under 10%. Our dryest month is February (also the shortest for sun), our hottest month is July, an average of 86 degrees F. January is our coldest month, the average 30 year low temperature is 28.
Acid rain is still prevalent in Pennsylvania, and soil fertility is directly impacted by the change to its PH, as is the affect on the aquatic ecosystem. Normal rain is 5.6PH.
Her handouts included quizzes to help us identify state waterbasins and rivers, and she included topographical maps as a resource for viewing. A watershed contributes to overland flow and groundwater to the stream or drainage basin. Small streams can be 1st order streams that actually don't always have water and are not as dependable as 2nd, 3rd or 4th order streams. Find basic facts about PA groundwater here.
As a farmer buying land, you need to be aware that water rights don't always come with land rights even if land is located within a watershed. As development occurs, more impervious surface results in more runoff and Welch noted the impact of land cover on surface water flow.
Camphill-Kimberton and Sankanac created a berm and swale to prevent erosion; they wanted their water resource to stay in place and infiltrate the soil.
Trees can be called inverted watersheds for moisture retention. Canopy covers like meadows and cover crops provide similar means of retaining moisture close to plant roots. Dr. Welch mentioned contour plowing to help water flow over the landscape.
She cited the Russian born German climatologist Wladimir Koppen, as one of the first scientists to map regions matching native plants. 'It is based on the concept that native vegetation is the best expression of climate; thus, climate zone boundaries have been selected with vegetation distribution in mind. It combines average annual and monthly temperatures and precipitation, and the seasonality of precipitation.'
Thanks to Dr. Welch for an energizing talk- she made geology a fascinating and integral aspect to any farming venture!
Stay tuned for next week's notes on Mike McGrath's seminar, 'Beneficial Creatures' at Rose Hall at Camphill-Kimberton on Wednesday evening June 10th, from 7pm -9pm. Public invited as always!
Happy growing! Schedule for all workshops here.