Nutrient Management Research Database

Research was conducted over four cropping systems to test three assumptions of site specific farming, aka Precision Agriculture, 1. that agronomically significant variability in plant growth, yield, pest pressures, environmental conditions, etc. exist within fields; 2. this variability can be measures; 3. the causes of yield or plant growth variability can be determined. This work tested three commercial fields cropped with wheat in 1995-1996, and tomatoes in 1997 against these assumption. Results indicate that tomato yield distribution was unrelated to wheat yield distribution in from the previous year in 2 fields. High clay content in the soils was correlated with low tomato yields and low wheat yields. Wheat yields were affected by the presence of grassy weeds. Low tomato yields in field 5 were correlated with low soil phosphate and early season petiole phosphate.

This research used aerial photographs, soil, and plant tissue to track yields and nutrient status of a wheat- tomato rotational cropping system in order to assess site specific farming conditions.

• Low tomato yields in one field were correlated with high clay content and with low phosphate content of the soil test and early season petiole tests.
• Low wheat yields were correlated with high clay content and high level of grassy weeds.
• Tomato yield distribution was unrelated to wheat yield distribution from the previous year in 2 fields.
• In other fields, low tomato yields and low wheat yields were correlated, likely related to high clay content in certain sections.
• High clay content in the soils affects wheat yield- low yields were recorded in areas with high clay content. T
• Tillage and maintenance of soil organic matter are key cultural practices that need to be monitored along with nutrients, pest, and soil variability.