4.7 Lettuce Components, sub-components and critical values for determining the suitability for summer grown lettuce are presented in Table 4.7. Table 4.7 Components, sub-components and sub-component critical values for determining the suitability for lettuce (summer crop 1:250 000). Components Critical Values Sub-components Highly suitable Generally Suitable Not Suitable 1 2 Class 3 Climate Mean January <28 28 maximum temperature (oC) Mean November >12 12-10 <10 Temperature (oC) Mean March >12 12-10 <10 Temperature (oC) Landscape Geomorphic unit 1.1, 1.2, 2.1, 2.3, 1.3, 2.2, 3.1, 3.5, 7.2, 2.4, 3.2, 3.3, 3.4, 8.5 4.1, 4.2, 5.1, 5.2, 6.2, 6.3, 7.1, 8.1, 8.2, 8.3, 8.4, 9.1, 9.2, 9.3 Landform F, L, P, E, R, W, I G S, Y, C Soil Soil type friable clays, friable earths duplex clays, stony earths, peaty clays, soils, saline soils sandy loams, sands Soil >1m <1m Structure Strong moderate to weak Stone content no stone high stone content pH highly acid/highly alkaline Salinity non saline saline Public land Freehold land public land
4.7 Lettuce Components, sub-components and critical values for determining the suitability for summer grown lettuce are presented in Table 4.7. Table 4.7 Components, sub-components and sub-component critical values for determining the suitability for lettuce (summer crop 1:250 000). Components Critical Values Sub-components Highly suitable 1 Generally Suitable 2 Not Suitable Class 3 Climate Mean January maximum temperature (oC) <28 28 Mean November Temperature (oC) >12 12-10 <10 Mean March Temperature (oC) >12 12-10 <10 Landscape Geomorphic unit 1.1, 1.2, 2.1, 2.3, 2.4, 3.2, 3.3, 3.4, 4.1, 4.2, 5.1, 5.2, 6.2, 6.3, 7.1, 8.1, 8.2, 8.3, 8.4, 9.1, 9.2, 9.3 1.3, 2.2, 3.1, 3.5, 7.2, 8.5 Landform F, L, P, E, R, W, I G S, Y, C Soil Soil type friable clays, friable earths, peaty clays, sandy loams, sands earths duplex clays, stony soils, saline soils Soil >1m <1m Structure Strong moderate to weak Stone content no stone high stone content pH highly acid/highly alkaline Salinity non saline saline Public land Freehold land public land
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