Title Simple Field Tests to Assess Soil Quality

Title Simple Field Tests to Assess Soil Quality in Precision Agriculture Apurba Sutradhar BAE/Soil 4213 April 28, 2010 apurba@okstate. edu

Soil Quality v The capacity of specific kind of soil to function. v To evaluate the soil’s ability to perform basic function Maintaining productivity Filtering and buffering against pollutants Storing and cycling nutrients. Source: USDA Soil Quality Test Kit Guide

Soil Quality Varies v Differences in agricultural practices Till Vs No till v Differences in crop growth areas Fast growth Vs Slow growth v Differences in slope Plain land Vs Slope land v Differences in wheel and non wheel areas Wheel Vs Non wheel v Differences in wet and dry areas Wet Vs Dry areas Source: USDA Soil Quality Test Kit Guide

Soil Quality Varies Also Field Variability can be determined by v Differences in soil type v Eroded and non-eroded areas v Row and inter -row areas Source: USDA Soil Quality Test Kit Guide

Assessing Soil Quality Two fundamental ways- v Take measurements periodically over time to monitor changes or trends in soil quality. v Compare measured values to a standard or referenced soil condition. Source: USDA Soil Quality Test Kit Guide

Soil Quality Testing Kit Developed by John Doran and associates, Agricultural Research Service, Lincoln, NE. Source: USDA Soil Quality Test Kit Guide

Soil Quality Testing Kit Soil Properties Chemical Physical Biological p. H Bulk Density Soil Respiration Electrical Conductivity Water content Earthworms Nitrate level Infiltration Rate Aggregate Stability Source: USDA Soil Quality Test Kit Guide

Soil Quality Testing Kit Advantages: v On farm test v Provide immediate results v Can be monitored changes in soil quality over time v Can be diagnosed soil health problems due to land use and management. v Simple- can be conducted by landowner and extension worker Source: USDA Soil Quality Test Kit Guide

Soil Quality Testing Kit An example- Soil Respiration Test Estimated time required : 40 minutes Source: USDA Soil Quality Test Kit Guide

Soil Quality Testing Kit An example- Soil Respiration Test CALCULATIONS: Soil Respiration (lb CO 2 -C/acre/day) = PF x TF x (%CO 2 - 0. 035) x 22. 91 x H PF = pressure factor = 1 TF = temperature factor = (soil temperature in Celsius + 273) ÷ 273 H = inside height of ring = 5. 08 cm (2 inches) Source: USDA Soil Quality Test Kit Guide

Planning-implementation-monitoring Set Goal Standard Value Scoring Data Applying Scoring Intervention Monitoring and Maintenance Courtesy: Dr. Kefyalew Desta

Data Collection and Scoring Steps Standard values Sum individual indicator values Scoring Sum component values Data collection General score and intervention Apply scoring system Individual indicator intervention Courtesy: Dr. Kefyalew Desta

Standard/Reference Values 3. 5 -5 (>3. 5)% >80 % <1. 1, <1. 4, <1. 6 : clayey, silty, sandy >40 0. 4 -2. 0, 0. 08 -1. 0, 0. 01 -0. 1 : sand, loam, clay SOM, % Aggregate, % BD, g/cm 3 Depth, in Infiltration rate, in/hr 2. 4 - 3. 5 Water holding, in/24 in soil 5. 8 -7. 3 p. H N-100% of yield goal P&K- 100% sufficient Fertility >50/50 -100 <0. 98 32 -64 345 -700 > 15 CEC, meq/100 g Courtesy: Dr. Kefyalew Desta EC , d. S/m Soil respiration, lbs CO 2 -C/a/d Soil microbial biomass mg , C/kg soil Earth worm, #

Scoring Courtesy: Dr. Kefyalew Desta

Applying the Scoring System Indicator Value and (corresponding score) Best Good Poor OM, % Physical properties 3. 5 -5 (25) 2. 5 -3. 5 (20) Water stable aggregation, % >80 (6) 60 -80 (4) Bulk density, g/cm 3 <1. 1, <1. 4, <1. 6 Depth, inch Infiltration rate, in/hr >40 (4) 0. 4 -2. 0, 0. 08 -1. 0, 0. 01 -0. 1 (4) Water holding capacity, 6 -9 (5) cm/60 cm soil Courtesy: Dr. Kefyalew Desta <2 (15) 50 -60 (2) (6) 1. 1<BD<1. 3, 1. 4<BD<1. >1. 4, >1. 6, >1. 7 (1) 6, 1. 6<BD<1. 7 (3) 20 -40 (3) <20 (2) ± 0. 2 of best value (3) ± 0. 4 of best value (2) 4 -6, 9 -10 (3) <4, >10 (1)

Applying the Scoring System Indicator Value and corresponding score (in parenthesis) Best Good Poor Chemical properties p. H (6) 5. 8 -7. 3 (6) Fertility ( N, P and N-100% of K), yield goal P&K- 100% sufficient (5) CEC, meq/100 g soil 50 -100 (5) EC (d. S/m @ 77 F) <0. 98 (4) Courtesy: Dr. Kefyalew Desta 5. 0 -5. 7, 7. 3 -8. 0 (4) N-80% of yield goal P&K- 80% sufficient (3) <5, > 8 (2) 16 -50 (3) N-< 80% of yield goal P&K- < 80% sufficient (1) <16 (1) 0. 98 - 1. 71 (3) >1. 71 (1)

Applying the Scoring System Indicator Value and corresponding score (in parenthesis) Best Good Poor Soil Biological Properties Soil respiration 32 -64 (10) 16 -32 (7) <16, >64 (4) lbs CO 2 -C/a/d Microbial 200 -345 (5) <200 (3) 345 -700 (8) biomass mg C/kg soil Earth worm 5 -15 (4) <5 (2) > 15 (7) (#/ft 2 in holes) Courtesy: Dr. Kefyalew Desta

Total Score and Intervention Total score Intervention type Description >90 Minor new Look for the indicator with lowest score and intervention; intervene with appropriate remediation continue with practices maintenance to avoid degradation 80 -90 Moderate intervention <80 Major and immediate Investigate the score of indicators in each intervention is component and apply comprehensive best required management practices. This level of soil quality warrants the need for raising soil organic matter level. Courtesy: Dr. Kefyalew Desta Look for the indicator with lowest score for each component and intervene with appropriate remediation practices.

Online Soil Quality Assessment This SQA algorithm is under construction

References and Links United States Department of Agriculture http: //usda. gov/wps/portal/usdahome Free Soil Quality Test Kit Guide can be downloaded from http: //soils. usda. gov/sqi/assessment/files/test_kit_complete. pdf Dr. Kefyalew Desta kefyalew. desta@okstate. edu

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