Soil biosolarization for sustainable strawberry production

Strawberry is a high value crop worth 315.6 million euros in 2013 in Spain. Strawberry diseases are commonly controlled by soil fumigation with toxic chemicals. However, since 2007, the methyl bromide fumigant is banned for strawberry cultivation. Moreover, European policies are progressively restricting the use of other toxic fumigants such as dichloropropene. Alternative control techniques are thus needed. Therefore, we have tested soil biosolarization, a new technique combining soil biofumigation and soil solarization, to cultivate the Camarosa strawberry in 2010–12 at Huelva in the southwestern coast of Spain. Soil was biofumigated by amendment of fresh chicken manure at 12,500 kg/ha with or without Trichoderma at 3.5 kg/ha; chicken manure at 25,000 kg/ha; Brassica juncea pellets at 2,000 kg/ha; sugar beet vinasse at 15,000 kg/ha; or dried olive pomace at 12,500 kg/ha. Soil was then solarized for 30 days by covering with a clear plastic mulch. A control that received fermented manure remained uncovered. Our results show that the highest yield averaging 70,543 kg/ha and the lowest percentage of 12.6 % of second-class fruits were obtained by amendment of fresh chicken manure. Yields were also similar to the higher yields previously reported for chemical fumigation with 1,3-dichloropropene and chloropicrin. In addition, biosolarization is about 20 % cheaper than treatment with 1,3-dichloropropene and chloropicrin. Biosolarization with chicken manure is, therefore, a promising sustainable option for strawberry production.