Sodic Calcareous Soil Reclamation as Affected by Different Amendments and Crops1

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Abstract
Sodium leaching efficiencies (moles of Na removed per unit leachate volume) were measured and compared from four noncropped and four cropped treatments applied in duplicate to 1.0 m deep sodic calcareous silt loam in lysimeters. Treatments included a check, gypsum, chopped alfalfa (Medicago sativa L.), fresh manure, alfalfa, sorghum (Sorghum bicolor), Sudan grass (Sorghum Sudanese) hybrid (which will be called sorghum hybrid for simplicity), sorghum hybrid + leaching, and cotton (Gossypium hirsutum L.). The sorghum hybrid + leaching treatment soil was leached with tap water until 0.5 pore volume of leachate was collected from lysimeter bottoms, and then sorghum hybrid was planted. Sorghum hybrid was the most efficient treatment in reclaiming Na‐affected soil. All four non‐cropped soils eventually became dispersed in the lower part of the profile and hydraulic conductivity became very low. Cropped treatments continued to conduct water at a satisfactory rate for reclamation; however, due to low water use, cotton treatment produced a low total Na removal. Sorghum hybrid shows promise as a crop that could be used to speed reclamation of sodic calcareous soils. The treatments producing the highest sodium removal efficiencies also produced the highest soil atmosphere CO2 concentrations. By selecting crops, amendments, and water application rates and timing, calcareous sodic soil reclamation can very likely be accomplished faster and more economically than in the past.