Intensive grid sampling often only include macronutrient analyses. This is helpful, but lacks the resolution of including other soil characteristics, such as micronutrients or soil texture. A previously created ¼ acre grid of the Warrington Irrigation
research farm revealed maps of micronutrients that were as interesting as the macronutrients. However, the patterns in the field did not indicate why there was variation, which could be relate to the original parent material. Sending selected samples off for texture analyses could determine the relationships of particle size to micronutrient analyses. This will also help determine water holding capacity and the potential for nematode infestations across the research farm.

1) Analyze grid soil samples for texture analyses

Soils were previously sampled in 2022 and again in 2024 on a ¼ acre grid sample at the Warrington Irrigation Research Farm in Harbeson, DE. Selected samples from these sets will be sent to the Penn State Soil Testing Lab for textural analyses.

Soil texture data will be entered into ArcGIS software and rasterized using kriging. These spatial maps of soil texture will be compared to macronutrients, micronutrients, and soil pH across the research farm. Relationships will be examined versus sand, silt, and clay content as well as a digital elevation model.

Future projects will be designed around the texture maps at the research farm.

Updated July 24, 2024:
Texture samples had been sampled from a previous grant at the Warrington Irrigation research farm. This allowed for quick shipping of the samples to the Penn State soil testing lab in July, 2024, with expected analyses completion by August 2024.

Updated January 3, 2025:
All texture samples were analyzed by Penn State soil testing for sand, silt, and clay content. Following delivery of the results, we geo-referenced each texture analyses with the sampling point at Warrington. This data was uploaded into ArcGIS where interpolated maps of texture were created using kriging so they can be compared to drone imagery and yield analyses of future and past projects. The maps of sand, silt, and clay have been used in presentations at regional meetings to describe the differences in soil nutrient content to field texture.

Updated April 3, 2025:

View uploaded report

This study explored how soil texture (sand, silt, and clay) affects nutrient availability in Delaware coastal plain soils, which can vary due to topographic differences. Sandy soils, possibly remnants of old sand dunes in this area, generally have lower nutrient retention capacity. These soils are more prone to nutrient leaching and may require more frequent fertilization to maintain adequate nutrient levels. In contrast, soils with more silt and clay, typically found in lower areas or depressions, have a better ability to retain nutrients, providing a more stable environment for plant growth.
These lower landscape positions may have higher clay content due to erosion, deposition, or weathering from greater water presence. As a result, these areas also contained higher amounts of aluminum (Al) and organic matter, both associated with clay and lower landscape positions. As expected, pH and buffer pH were linked to clay content across the field, where clay's higher buffering capacity typically leads to more acidic conditions.
Silt-rich soils may have originated from loess, which also contributes to better nutrient retention. Micronutrients like manganese and copper were more available in finer soils (silt and clay) due to their higher nutrient-holding capacity. These micronutrients may also be related to the parent material itself, further enhancing micronutrient content. Zinc, however, did not show a clear relationship with soil texture, suggesting that other factors, such as past management practices, could influence its availability.
Understanding how soil texture, elevation, and parent material affect nutrient availability can help farmers optimize fertilization practices, manage pH levels, and improve overall soil health. This knowledge can lead to better crop productivity and more sustainable farming practices.

Grid sampling of texture is not often performed and can potentially be tied to the variable fertility in our coastal soils.