Chapter 11

Monitoring Nutrient Status

(book excerpts)

Monitoring nutrient levels within tissue and soil represents an important step in maximizing crop yield. There are three basic tools available for monitoring nutrient status: (1) field observations, (2) plant tissue analysis, and (3) soil analysis (soil testing). It is not possible to rely on visual symptoms of nutrient deficiency as single element since symptoms can often be confused with each other or with disease or other stresses. Also, once the deficiency has manifested itself by way of a symptom, the yield penalty may have already occurred. In many cases plants will not show obvious signs of a deficiency even though crop growth may be restricted. This reinforces the need to undertake plant tissue and soil testing as a regular means of monitoring crop growth and performance. Analysis of plant tissues is an extremely useful tool for growers. Not only can plant tissue testing be used to monitor the nutrient status of plants but it can help identify nutrient deficiencies and imbalances. This allows growers to more effectively tailor their nutrient management programs to meet a crop's specific needs. Regular soil testing is an important element in nutrient management too. Soil tests are used to measure soil nutrients that are expected to become plant-available. They do not measure the total amounts of nutrients in soil. Measurements of total nutrient content are not useful indicators of sufficiency for plant growth, because only a small portion of the nutrients are plant-available. All three approaches should be integrated to effectively guide the application of nutrients, as well as to diagnose problems as they arise in the field. Precision agriculture technologies have potential to improve soil fertility management in a sustainable manner. In this context, these technologies, along with other systems like global positioning system (GPS) and geographic information systems (GIS), can be used to help growers monitor nutrient status of crop and soil in a cost effective and timely manner.

Topics Within This Chapter:

  • Field Observations
  • Plant Analysis
  • Plant Tissue Analysis
  • Plant Tissue Testing for Nitrate
  • Soil Analysis
  • Soil Sampling
  • Sampling Methods
  • Time of Sampling
  • Sampling Tools
  • Sampling Depth
  • Sample Handling and Record Keeping
  • Soil Tests
  • Testing for Nitrogen
  • Soil Test Recommendations
  • Soil Test Ratings
  • Fertilizer Recommendations
  • Remote Sensing in Precision Agriculture
  • The Electromagnetic Spectrum
  • Image Resolution
  • Spatial Resolution
  • Spectral Resolution
  • Temporal Resolution
  • Radiometric Resolution
  • Platforms Used in Remote Sensing
  • Satellites
  • Aircraft
  • Unmanned Aerial Vehicles
  • Ground-Based Technologies
  • Proximal Sensing Applications
  • Soil Assesment
  • Fertilizer Management
  • Plant Health Assessment