our reporter holger trzeczak went along to find out more.reporter: this farmer had to take out a small loan to be able to plant his sugar cane. but it's still not clear whether he can cover those costs. everything looks lush and green to the untrained eye. surely the 1000-euro loan shouldn't be a problem. but the farmer says it's far from a bumper harvest. jesus chicaisa castillo: whether we sow beans or corn, we lose a lot of our crop. the sugar cane up there has basically dried out. and the stuff back there looks a lot better than it is. reporter: we've come to the province of narino, in southern colombia. this area is in the andes, at an altitude of 2,500 meters. much of it is farmland. climate change has made the harvest increasingly unpredictable. so farmers are relying more than ever on extra help. chemical pesticides and fertilizers may keep pests away, but they also strip the soil of nutrients. the concept of environmentally sustainable farming is not yet widespread in colombia. but in the regional capital pasto, a start is being mad