*2.1.2. Waste Water effects on the herbaceous crops*

The effects of the WW distribution on soils destined to herbaceous crops, vary according to the WW composition, the quantity, the distribution dates in relationship to seeding or crop phenologic stage, the rainfall after the WW supply.

The olive mill WW do not generally affect the productivity of the spring-summer crops, when the shedding is effected with an adequate interval time before the seeding. It is also possible to distribute the WW with crop in action, i.e. on autumn-winters cereals, in the full growth phase, limiting the WW doses to not over 40 m3 ha-1 (Bonari et al., 1993; Di Giovacchino & Seghetti, 1990; Di Giovacchino et al., 2001; Marsilio et al., 1990; Montemurro et al., 2007, 2011*a*; Roig et al., 2006).

Negative effects on grass crops are due to the elevated values of electrical conductivity, that can induce salinity damages, flocculation of soil clay fraction, the phytotoxicity of poliphenols (Della Monica et al., 1978, 1979).

In the last years, because of environmental protection policy, new technologies that minimize these risks were developed. In this framework, the raw olive waste water was differently treated to improve the percentage of recycle of these materials. In particular, different studies indicate that the application of mineral catalyser (MnOX) on WW reduces the level of poliphenols and other pollutants. As a consequence, this treatment decreases both phytotoxicity and temporary immobilization of soil mineral N, thus making the treated WW able to sustain good levels of crops yield and products quality (Montemurro et al., 2007; Vigo et al, 1990).
