Fertilization Management of Paddy Fields in Piedmont (NW Italy)

A well-documented analysis of fertilization management techniques in use by farmers in a given region is the first step to improving the management standards of agronomic practices. The aim of this work was to summarize the fertilization management that farmers normally utilize for the rice crop in the Piedmont Region of Northwest Italy, and to analyze its agronomic and environmental sustainability. On average, 127 kg ha-1 of N, 67 kg ha-1 of P2O5, and 161 kg ha-1 of K2O were applied to the rice crop. Inorganic fertilizers were used on most of the surface. Calcium cyanamide was the most widely used slow-release product. Commercial organic compounds were spread on about 32% of the paddy surface, while farmyard manure was distributed over 6% of the surface. Organic-mineral products were also widely used. One fourth of the paddy surface received only inorganic products. Using organic or organic-mineral fertilizers together with inorganic products was the most common strategy (55% of the paddy surface). In most cases, N and P fertilization was balanced with crop removal. The N soil surface balance was in the ± 50 kg range for 77% of the surface, P fertilization was less than removal for 53% of the surface, whereas K fertilization was excessive (surplus >100 kg ha-1) for 53% of the surface. The nutrient balance was affected by the widespread practice of burning straw after harvest (66% of the paddy surface). The farmers modulated fertilization according to the rice variety requirements and tolerance to high N supply. The largest nutrient surplus was associated with stocking farms. Inefficient use of fertilizers that should be avoided to improve the territorial nutrient balance were then outlined, and possible specific actions were proposed.