Soil solarization: Effects on soil properties,crop fertilization and plant growth

Summer solarization of six wet field soils of four different textures raised soil temperatures by 10–12°C at 15cm depth. Soil solarization increased concentrations of NO^?₃N and NH⁺₄N up to six times those in nontreated soils. Concentrations of P, Ca²⁺, Mg²⁺ and electrical conductivity (EC) increased in some of the solarized soils. Solarization did not consistently affect available K⁺, Fe³⁺, Mn²⁺, Zn²⁺, Cu²⁺, Cl^? concentrations, soil pH or total organic matter. Concentrations of mineral nutrients in wet soil covered by transparent polyethylene film, but insulated against solar heating, were the same as those in nontreated soil. Increases in NO^?₃N plus NH⁺₄N were no longer detected in fallowed soils 9 months after solarization. No significant correlation between mineral-nutrient concentration in plant tissue and plant growth was found. Fresh and dry weights of radish, pepper and Chinese cabbage plants usually were greater when grown in solarized soils than in nontreated soils. Fertilization of solarized soils sometimes resulted in greater plant growth responses than observed in solarized but nonfertilized soils.