Mean organic crop yields (ton/ha) by conventional crop yield data pair availability (Figure S1 & S2)

Group Crop DataPair YieldMean
Field Crops Barley Conventional data pair available 2.64
Field Crops Barley No conventional data pair 1.97
Field Crops Dry edible bean Conventional data pair available 1.57
Field Crops Dry edible bean No conventional data pair 1.05
Field Crops Maize (grain) Conventional data pair available 7.08
Field Crops Maize (grain) No conventional data pair 6.44
Field Crops Maize (silage) Conventional data pair available 36.35
Field Crops Oat Conventional data pair available 2.01
Field Crops Oat No conventional data pair 2.03
Field Crops Sorghum (silage) Conventional data pair available 26.61
Field Crops Sorghum (silage) No conventional data pair 24.60
Field Crops Soybean Conventional data pair available 2.12
Field Crops Soybean No conventional data pair 2.03
Field Crops Wheat (all) Conventional data pair available 2.44
Field Crops Wheat (all) No conventional data pair 1.88
Fruit & Tree Crops Apple Conventional data pair available 12.19
Fruit & Tree Crops Apple No conventional data pair 10.26
Fruit & Tree Crops Avocado Conventional data pair available 5.70
Fruit & Tree Crops Blackberry Conventional data pair available 4.88
Fruit & Tree Crops Blackberry No conventional data pair 2.75
Fruit & Tree Crops Blueberry Conventional data pair available 4.26
Fruit & Tree Crops Blueberry No conventional data pair 0.64
Fruit & Tree Crops Cantaloupe Conventional data pair available 10.86
Fruit & Tree Crops Cantaloupe No conventional data pair 8.19
Fruit & Tree Crops Cherry, sweet Conventional data pair available 7.41
Fruit & Tree Crops Cherry, sweet No conventional data pair 3.46
Fruit & Tree Crops Fig Conventional data pair available 4.19
Fruit & Tree Crops Fig No conventional data pair 4.48
Fruit & Tree Crops Grapefruit Conventional data pair available 25.67
Fruit & Tree Crops Grapefruit No conventional data pair 10.85
Fruit & Tree Crops Grapes Conventional data pair available 5.54
Fruit & Tree Crops Grapes No conventional data pair 2.71
Fruit & Tree Crops Lemon Conventional data pair available 28.45
Fruit & Tree Crops Orange Conventional data pair available 18.68
Fruit & Tree Crops Orange No conventional data pair 3.35
Fruit & Tree Crops Peach Conventional data pair available 9.86
Fruit & Tree Crops Peach No conventional data pair 9.80
Fruit & Tree Crops Pear Conventional data pair available 13.93
Fruit & Tree Crops Pear No conventional data pair 11.98
Fruit & Tree Crops Plum/Prune Conventional data pair available 5.80
Fruit & Tree Crops Plum/Prune No conventional data pair 6.28
Fruit & Tree Crops Raspberry Conventional data pair available 7.08
Fruit & Tree Crops Raspberry No conventional data pair 1.21
Fruit & Tree Crops Strawberry Conventional data pair available 10.49
Fruit & Tree Crops Strawberry No conventional data pair 11.77
Fruit & Tree Crops Watermelon Conventional data pair available 15.46
Fruit & Tree Crops Watermelon No conventional data pair 13.26
Vegetables Artichoke Conventional data pair available 15.61
Vegetables Artichoke No conventional data pair 12.18
Vegetables Bean, snap Conventional data pair available 5.19
Vegetables Bean, snap No conventional data pair 5.15
Vegetables Broccoli Conventional data pair available 16.20
Vegetables Broccoli No conventional data pair 6.14
Vegetables Carrot Conventional data pair available 14.71
Vegetables Carrot No conventional data pair 10.33
Vegetables Cauliflower Conventional data pair available 12.05
Vegetables Cauliflower No conventional data pair 5.46
Vegetables Celery Conventional data pair available 50.76
Vegetables Celery No conventional data pair 10.49
Vegetables Garlic Conventional data pair available 5.03
Vegetables Garlic No conventional data pair 3.07
Vegetables Lettuce (all) Conventional data pair available 14.73
Vegetables Lettuce (all) No conventional data pair 9.37
Vegetables Maize (sweet) Conventional data pair available 7.85
Vegetables Maize (sweet) No conventional data pair 4.02
Vegetables Onion Conventional data pair available 20.26
Vegetables Onion No conventional data pair 11.48
Vegetables Pea Conventional data pair available 7.21
Vegetables Pea No conventional data pair 15.10
Vegetables Pepper, bell Conventional data pair available 16.41
Vegetables Pepper, bell No conventional data pair 8.13
Vegetables Potato Conventional data pair available 16.81
Vegetables Potato No conventional data pair 6.14
Vegetables Spinach Conventional data pair available 7.10
Vegetables Spinach No conventional data pair 5.61
Vegetables Squash Conventional data pair available 12.66
Vegetables Squash No conventional data pair 9.41
Vegetables Sweet potato Conventional data pair available 20.31
Vegetables Sweet potato No conventional data pair 8.97
Vegetables Tomato Conventional data pair available 16.36
Vegetables Tomato No conventional data pair 11.65

Min. 1st Qu. Median Mean 3rd Qu. Max. 0.3200 0.5600 0.6800 0.6872 0.7600 1.2000

Field & Forage Crops

Median and weighted mean yield ratios for field & forage crops (Manuscript Fig 1).

Crop NumStates MedianRY RelYield
5 Barley 18 0.65 0.76
19 Dry edible bean 11 0.62 0.74
25 Hay & alfalfa mix 28 0.94 1.00
26 Hay (all) 39 1.14 1.12
27 Haylage 15 0.87 0.76
28 Hay (other) 31 1.12 1.20
34 Maize (grain) 26 0.66 0.65
35 Maize (silage) 23 0.77 0.78
37 Oat 21 0.74 0.80
53 Soybean 19 0.69 0.68
62 Wheat (all) 29 0.63 0.66
64 Wheat (spring) 7 0.71 0.70
65 Wheat (winter) 25 0.63 0.66

Dry edible bean production data by state

State Organic farms Organic hectares Organic yield (ton/ha) Total hectares Total yield (ton/ha) Yield ratio
Arizona 6 2967 2.98 4413 2.17 1.376
New York 8 223 1.98 3117 1.67 1.183
Idaho 10 143 2.23 50202 2.02 1.107
Michigan 49 2441 1.90 99312 2.17 0.878
North Dakota 5 391 1.08 248988 1.60 0.673
Minnesota 8 296 1.27 59919 2.18 0.582
California 6 298 1.34 19231 2.45 0.549
Nebraska 4 174 1.53 61538 2.80 0.546
Montana 8 445 0.88 14980 1.83 0.482
Colorado 14 474 0.96 17814 2.13 0.450
Wisconsin 8 569 1.13 3198 2.78 0.407

The median yield ratio for dry edible bean was 0.62, substantially less than the weighted mean yield ratio of 0.74. Of the 11 states where both organic and conventional dry edible bean were grown in 2014, only 3 reported organic yields greater than conventional yield (Table 2). Arizona had the greatest organic dry edible bean area (35% of the total) and also had the greatest yield ratio (1.38). The top four states for conventional dry bean area (Michigan, North Dakota, Minnesota, and Nebraska) had much lower organic yield compared to conventional (average weighted yield ratio of 0.67).

It is unclear why such a difference between states was observed with organic to conventional yield ratio in dry edible bean. Since it is a legume, nitrogen deficiency should play a minimal role in contrast to many other organic crops, as long as the seed is inoculated with the appropriate rhizobium species. Idaho and Colorado represent relatively similar growing environments with respect to dry edible bean production, and conventional yields were similar between these two states (Table 2). Even though conventional yields were similar, organic to conventional yield ratios of 1.11 and 0.45, were observed in Idaho and Colorado, respectively, because organic dry bean yield was much lower in Colorado. Regardless of the reason for the difference, these results suggest that dry edible bean has potential to be grown under organic management practices without sacrificing yield, but that potential is not being met in most organic production areas.

Barley production data by state

State Organic farms Organic hectares Organic yield (ton/ha) Total hectares Total yield (ton/ha) Yield ratio
Washington 13 211 3.67 42510 3.23 1.137
Oregon 31 3330 2.75 12146 2.69 1.022
California 21 1495 3.82 10121 3.92 0.973
North Dakota 7 709 3.23 216599 3.60 0.897
Wisconsin 122 1705 2.21 6478 2.53 0.874
South Dakota 7 260 2.27 6883 2.80 0.811
Minnesota 58 1319 2.25 24291 2.80 0.804
New York 29 454 2.00 3239 2.53 0.793
Michigan 9 54 2.05 2834 2.85 0.718
Pennsylvania 27 155 2.71 20243 3.82 0.710
Colorado 4 422 4.22 21862 6.66 0.633
Arizona 3 221 4.01 12955 6.72 0.597
Virginia 8 146 2.48 11336 4.25 0.583
Maine 9 98 2.08 4858 3.65 0.570
Idaho 46 5105 2.61 206478 5.05 0.516
North Carolina 7 145 1.85 6073 3.82 0.484
Maryland 9 182 1.85 18219 4.14 0.448
Montana 17 840 1.39 311741 3.12 0.447

The median yield ratio for barley was substantially less than the weighted mean yield ratio (Table Xbarley). Of the 18 states reporting both conventional and organic barley yield, only 2 (Washington and Oregon) had a yield ratio greater than 1. In general, the states with the most organic farms reporting had yield ratios closer to 1 compared to states with fewer organic farms. The most notable exception to this trend was Idaho. Idaho had the largest area devoted to organic barley production (5105 hectares) and the greatest number of organic barley farmers responding to the survey (46), yet had among the lowest yield ratios, with organic barley yielding 52% of conventional barley. Idaho was the second leading producer of conventional barley in terms of area in 2014, producing over 200,000 hectares.

Haylage production data by state

State Organic farms Organic hectares Organic yield (ton/ha) Total hectares Total yield (ton/ha) Yield ratio
Texas 6 413 18.2 63563 12.5 1.458
Ohio 89 1847 12.7 53846 11.4 1.118
Washington 45 2251 16.7 41700 16.5 1.014
Illinois 7 188 13.2 19838 14.3 0.925
Missouri 6 205 10.0 36437 11.0 0.911
Iowa 61 1166 11.6 62753 13.5 0.859
South Dakota 6 626 12.5 24291 14.7 0.853
California 50 5257 22.8 97166 28.2 0.806
Vermont 95 6174 11.3 56680 14.2 0.791
Michigan 18 332 14.2 117409 18.0 0.788
Wisconsin 232 8950 12.0 540486 16.0 0.755
Minnesota 67 2660 9.7 149798 14.3 0.673
Pennsylvania 150 4007 9.2 182186 13.9 0.664
Idaho 4 244 15.3 48583 24.3 0.631
New York 193 8299 8.5 267206 13.9 0.609

Of the 15 states reporting both organic and conventional haylage yields, all reported greater organic haylage yields compared to conventional (Table Xhay). The organic to conventional haylage yield ratios ranged from 1.4 to 3.7. States with the greatest number of organic farms and organic area tended to have lower yield ratios, which resulted in a weighted mean substantially less than the median yield ratio for haylage (Fig 1).

Fruits and Vegetables

Median and weighted mean yield ratios for fruit & vegetable crops (Manuscript Fig 2).

Crop NumStates MedianRY RelYield
Apple 16 0.29 0.60
Blueberry 9 0.62 0.56
Grapes 7 0.61 0.50
Maize (sweet) 16 0.73 0.77
Onion 7 0.41 0.40
Peach 7 1.07 0.67
Pepper, bell 7 0.46 0.48
Potato 20 0.26 0.38
Snap bean 11 0.75 0.75
Squash 11 0.72 0.74
Tomato 15 0.58 0.50
Watermelon 9 0.61 0.32

Peach production data by state

State Organic farms Organic hectares Organic yield (ton/ha) Total hectares Total yield (ton/ha) Yield ratio
Arkansas 3 1 13.4 263 2.2 6.000
Washington 36 109 23.0 972 11.7 1.971
Georgia 4 0 9.0 4413 7.3 1.227
Texas 7 1 3.4 1255 2.8 1.220
California 142 668 17.2 17814 31.6 0.545
Utah 4 0 2.2 526 11.2 0.200
Pennsylvania 9 6 0.8 1619 8.4 0.096

Median peach yield ratio was greater than 1, while the weighted mean was less than 1. The difference between the median and mean for the peach yield data was influenced by many states with very few organic acres in production (Table 3). Four of the seven states reporting both organic and conventional peach yield data had yield ratios greater than 1, but these states produced relatively few organic hectares (and had relatively few organic farms). Arkansas, for example, had a yield ratio of 6.0, but only 3 organic farms producing a total of 1 organic hectare. Georgia, the state with the second highest area of conventional peach production, had less than 1 organic hectare represented in the comparison. Washington and California, the two states with the largest number of organic farms and area, had yield ratios of 1.97 and 0.55, respectively. We were unable to find an explanation for the large difference between the yield ratios from Washington and California. It may relate to the ratio of processing to fresh market production in each state, and within each system within a state, since production issues like early frost and pest management can be less problematic for processing than for the fresh market.

Apple production data by state

State Organic farms Organic hectares Organic yield (ton/ha) Total hectares Total yield (ton/ha) Yield ratio
Colorado 17 79 20.3 486 8.3 2.440
Ohio 3 0 26.9 1457 13.7 1.966
Utah 5 5 21.9 526 19.8 1.103
California 245 1227 14.4 6073 17.9 0.806
Washington 221 4523 43.0 59919 55.2 0.778
New York 24 65 20.1 16194 36.3 0.554
Oregon 71 111 16.9 2065 34.0 0.498
Minnesota 28 46 4.3 1053 10.8 0.402
Maine 27 58 6.1 1093 15.8 0.390
Wisconsin 47 43 4.6 1619 15.1 0.305
North Carolina 11 5 4.1 2429 23.3 0.178
Massachusetts 6 9 2.5 1255 15.6 0.161
Maryland 7 4 4.1 729 25.8 0.158
Virginia 9 7 2.6 4211 21.0 0.124
New Hampshire 11 4 1.2 526 14.6 0.083
Idaho 9 2 2.0 972 29.5 0.067

The median yield ratio for apple was much lower than the weighted mean (Fig 2). The median was influenced by a large number of states with less than 10 hectares of organic apples that had organic yields less than 20% of conventional (Table Xapple). The two states with the greatest organic production both in terms of farms and area (California and Washington) had organic yield that was 81% and 78% of conventional, respectively, compared to the weighted mean of 60% of conventional for all states reporting both conventional and organic apple production.

Potato production data by state

State Organic farms Organic hectares Organic yield (Ton/ha) Total hectares Total yield (ton/ha) Yield ratio
Washington 60 528 60.6 66802 68.9 0.880
Colorado 15 1426 33.5 24211 43.4 0.772
Wisconsin 69 93 33.2 25911 45.9 0.724
Maine 68 166 20.0 20445 32.5 0.617
Idaho 13 31 26.1 129555 46.5 0.561
California 82 1161 28.6 13401 52.6 0.543
Oregon 44 1257 31.1 15749 64.9 0.478
Texas 14 11 17.8 8340 37.5 0.475
Pennsylvania 44 29 10.3 2105 30.8 0.335
Massachusetts 31 9 10.3 1457 31.9 0.322
Minnesota 33 4 12.9 16599 44.8 0.289
Ohio 42 8 9.1 607 31.4 0.289
Michigan 17 2 10.5 17206 41.4 0.254
New York 58 27 5.6 6397 30.8 0.182
Illinois 19 3 8.0 2591 46.5 0.172
Kansas 11 2 6.0 1660 38.1 0.157
Maryland 14 4 5.4 931 42.6 0.126
North Carolina 36 13 2.8 5466 23.5 0.120
Virginia 17 10 2.9 1822 28.0 0.105
Florida 5 2 1.6 11862 26.9 0.058

Potato may be among the most difficult crops to grow organically relative to conventional. Organic potato yield was only 38% of conventional potato yield in our analysis, and the median was even lower, at 26% of conventional yield (Fig 2). None of the 20 states in our analysis reported organic yields greater than conventional, and only one state (Washington) reported organic potato yield more than 80% of conventional (Table Xpotato).

Grape production data by state

State Organic farms Organic hectares Organic yield (Ton/ha) Total hectares Total yield (ton/ha) Yield ratio
Oregon 55 472 6.4 7692 6.8 0.931
Washington 71 946 13.0 29150 15.9 0.816
New York 22 74 8.8 14980 11.4 0.770
California 533 9443 8.4 350202 17.7 0.474
North Carolina 4 12 1.4 931 5.8 0.238
Georgia 16 5 0.7 648 5.6 0.124
Michigan 9 9 0.2 5506 10.4 0.022

Of the seven states that reported both organic and conventional grape yields, none had yield ratios greater than 1. The grape yield ratio may be skewed somewhat in California (the largest grape producer for both organic and conventional) because organic wine grapes are often produced in low yielding coastal areas, while the conventional data includes the higher yielding Central Valley of California.

Weighted and unweighted slope parameters regressing yield ratio onto conventional yield (Manuscript Fig 4)

Crop Unweighted slope SE P Rsq Weighted slope SE P Rsq
Apple -0.005 0.024 0.836 0.003 0.007 0.009 0.468 0.038
Barley -0.093 0.052 0.092 0.167 -0.166 0.052 0.005 0.393
Blueberry -0.017 0.035 0.640 0.033 -0.031 0.033 0.373 0.114
Dry edible bean -0.462 0.320 0.183 0.188 -0.508 0.396 0.231 0.155
Grapes 0.078 0.121 0.546 0.077 0.001 0.061 0.982 0.000
Hay & alfalfa mix -0.056 0.015 0.001 0.354 -0.065 0.016 0.000 0.393
Hay (all) -0.076 0.020 0.000 0.285 -0.083 0.016 0.000 0.425
Haylage -0.017 0.013 0.210 0.118 -0.003 0.015 0.872 0.002
Hay (other) -0.199 0.060 0.002 0.275 -0.203 0.035 0.000 0.530
Maize (grain) -0.077