1. Sensor Based Technology for Predicting Soil Organic Carbon (Organic Matter) Kent Martin

2. Organic matter is the most complex, dynamic, and reactive soil component. Because of the importance of organic matter in soils, its estimation is important in disciplines ranging from soil fertility, chemistry, and physics to land planning and soil productivity. Soil Organic Matter: Analysis and Interpretation

3. ORGANIC MATTER MESQUITE RHIZOBIUM ALFALFA SOYBEAN BLUE-GREEN ALGAE AZOTOBACTER CLOSTRIDIUM PLANT AND ANIMAL RESIDUES R-NH 2 + ENERGY + CO 2 R-NH 2 + H 2 O R-OH + ENERGY + 2NH 3 MATERIALS WITH N CONTENT < 1.5% (WHEAT STRAW) MATERIALS WITH N CONTENT > 1.5% (COW MANURE) MICROBIAL DECOMPOSITION HETEROTROPHIC AMINIZATION BACTERIA (pH>6.0) FUNGI (pH<6.0) AMMONIFICATION GLOBAL WARMING pH>7.0 2NH 4 + + 2OH - FIXED ON EXCHANGE SITES +O 2 Nitrosomonas 2NO 2 - + H 2 O + 4H + IMMOBILIZATION NH 3 AMMONIA-3 NH 4 + AMMONIUM-3 N 2 DIATOMIC N0 N 2 O NITROUS OXIDE1 NO NITRIC OXIDE2 NO 2 - NITRITE3 NO 3 - NITRATE5 OXIDATION STATES ATMOSPHERE N 2 O NO N 2 N2O2-N2O2- NH 3 SYMBIOTICNON-SYMBIOTIC + O 2 Nitrobacter FERTILIZATION LIGHTNING, RAINFALL N2 FIXATION DENITRIFICATION PLANT LOSS AMINO ACIDS NO 3 - POOL LEACHING AMMONIA VOLATILIZATION NITRIFICATION NH 2 OH Pseudomonas, Bacillus, Thiobacillus Denitrificans, and T. thioparus MINERALIZATION + NITRIFICATION IMMOBILIZATION NO 2 - MICROBIAL/PLANT SINK TEMP 50°F pH 7.0 LEACHING DENITRIFICATION LEACHING VOLATILIZATION NITRIFICATION ADDITIONS LOSSES OXIDATION REACTIONS REDUCTION REACTIONS HABER BOSCH 3H 2 + N 2 2NH 3 (1200°C, 500 atm) INDUSTRIAL FIXATION

4. (SSCM) Site-specific Crop Management Hummel and Sudduth Aims to improve production efficiency by adjusting crop treatments to varying local conditions within the field. Sudduth

5. Optical Sensor Uses NIR reflectance data at many different narrow-banded wavelengths More complex, but more expensive and less durable than single-band sensor Intended use: soil organic matter

6. Steps of sensor operation 1.Emit light using fiber optics 2. Light is reflected from soil surface 3.Light is captured by photodetector 4.Data is sent to PC

7. Effective Sensing Range 1630- 2650nm

8. Prediction of organic carbon in the laboratory

9. Prediction was based on many variable soil types and variable moisture contents. Accuracy for SOM r^2= 0.89 Accuracy for moisture r^2= 0.94

10. Benefits Gives a way to measure soil organic matter Measures soil moisture Can be added to data layers for specific fields to generate maps

11. Negative Points Expensive Low durability Not yet acceptable for use in field

12. Possible uses of sensor Estimation of soil organic matter Soil structure Water holding capacity Infiltration of water and air Reduction of soil erosion

13. References Hummel, John W. Within-field Location and Sensing Technology. 04/18/01 www. odyssey.maine.edu/gisweb/spatdb/acsm/ac9 4071 OSU. Oklahoma Soil Fertility Handbook. 2000 Magdoff, F. R. Soil Organic Matter: Analysis and Interpretation. 1996