SOIL ENZYME ACTIVITIES, MICROBIAL COMMUNITIES, AND CARBON AND NITROGEN AVAILABILITY IN ORGANIC AGROECOSYSTEMS ACROSS AN INTENSIVELY-MANAGED AGRICULTURAL LANDSCAPE - Organic Agricultural Practices - page 283

TABLE 1: Field management and soil types at the 13 organic tomato fields in Yolo County,
California, USA.

Field Years in organic a Primary organic

inputs b

Secondary nutrient
inputs c

Soil type d

1 4 Manure None Tehama loam

2 8 Manure None Tehama loam

3 NA Manure None Capay silty clay

4 3 Vetch Guano, soluble Tehama loam

5 8 Manure, vetch None Capay silty clay

6 11 Manure, vetch Guano Brentwood silty clay

loam

7 3 Compost, vetch Pellets, soluble Yolo silt loam

8 2 Compost Pellets, soluble Yolo silt loam

9 11 Manure, vetch Guano Yolo silt loam

10 8 Compost Chilean nitrate Yolo silt loam

11 5 Compost Chilean nitrate Yolo silt loam

12 26 Compost Soluble Yolo silt loam

13 8 Compost Chilean nitrate Yolo silt loam

a Years since certification (does not include transition years). This information was not
available for field 3, but it is certified organic.
b Compost and manure were applied in fall 2010, with the exception of field 5, in which
manure was applied in early spring prior to tomato transplanting. Winter vetch cover crops
were incorporated prior to transplanting. Compost was composted green waste with a C:N
ranging from 15 to 18. Manure was poultry manure or poultry litter with a C:N ranging
from 9.8 to 15.
c Guano refers to seabird guano (12-12-2.5). Pellets were pelletized poultry manure
(6-3-2). Chilean nitrate (16-0-0) is NaNO3, a mined mineral product. Soluble refers to
solubilized organic fertilizers, especially fish emulsions, which have a range of nutrient
concentrations. Guano, pellets, and Chilean nitrate were all applied as a sidedressing
close to tomato transplanting. Small amounts (less than 7 kg-N ha−1) of soluble fertilizers
are applied through the drip line periodically throughout the growing season.
d Tehama loam: fine-silty, mixed, superactive, thermic Typic Haploxeralfs; Capay silty
clay: fine, smectitic, thermic Typic Haploxererts; Brentwood silty clay loam: fine, smectitic,
thermic Typic Haploxerepts; Yolo silt loam: fine-silty, mixed, superactive, nonacid, thermic
Mollic Xerofluvents