Two trials in different agricultural farms were carried out from October 2014 to June 2015 with the aim to assess the advantages linked to the substitution of the low density polyethylene (LDPE) films for soil mulching with the Mater-Bi ® biodegradable films in the strawberry cultivation under tunnel in Campania. Lifetime of biodegradable mulch and influence of type of mulch on the yield and the quality of cvs Sabrina and Fortuna were evaluated. Plants were cultivated on mulched, raised beds, high 40 cm from bottom soil. Mater-Bi ® film was 20 μm thick while LDPE film was 50 μm thick. The physical-chemical parameters (firmness, pH, total soluble solid content, titratable acidity and skin colour) and some bioactive compounds (total polyphenols, flavonoids, anthocyanins, antioxidant activity) of fruits were determined by three samplings effected in consecutive months (from March to May 2015) of the harvest cycle. Biodegradable film guaranteed an effective mulch along the whole strawberry cycle (9-10 months including the time of drawing up of film). Yields of cv Sabrina on LDPE was 18% higher than those on Mater-Bi ® while the opposite was detected in cv Fortuna (+10%). The physical-chemical parameters of fruits were not modified by the mulches. The content of the bioactive compounds, instead, resulted, in each time of sampling, significantly higher in fruits picked on Mater-Bi ® based film.

In a farm devoted to the production of fresh-cut leafy vegetables located in Eboli (Salerno), it was carried out a trial to compare the effects on crops and soil organic carbon (SOC) of biowaste compost, olive pomace compost, buffalo manure applied to soil in two doses (15 and 30 t ha⁻¹ fresh weight). The amendments were tested in order to start in defining a feasible strategy for the recovery/maintenance of soils in degradation due to the organic matter depletion triggered by the intensive soil tillage and the lack of organic matter returned to soil. In the year following the soil amendment, it was studied the crop sequence: rocket-basil-rocket. Analysis of nitrates concentration in leaves of rocket was carried out on samples of all the treatments picked up in the two cycles of rocket. Along the year, we observed that the higher yields promoted in the first six months (May-September) from the dose 15 t ha⁻¹, were obtained with the dose 30 t ha⁻¹ in the successive six months (November-May). This was due, probably, to the larger stock of total N supplied with dose 30 and its release in time. Buffalo manure amendment showed a higher quickness than composts in the supplying mineral nitrogen to the first crops. On the other hand, nitrates in leaves of rocket exceeded, more frequently, the limits fixed in EU Regulation n. 1258/2011 in the plots amended with buffalo manure. Instead, the treatments with olive pomace compost showed to exceed rarely the EU limits. Under tunnel, the intensive management based on 4-5 crop cycles per year and as much soil tillage, appeared the first cause to explain the lack of significant variation in SOC of plots treated with organic improvers after one year from their distribution. This result let us to suppose the need to study some modifications of the standard farm management in order to reduce the number of soil tillage in a year and, as a consequence, the main stress causing the high carbon mineralisation rate in soil under tunnel.

This paper deals with the introduction in tunnel-greenhouses of sweet sorghum cultivated in short, summer cycle as green manure with the aim to amend soils with biomass grown on farm. This practice has been spreading in tunnels of Sele river Valley (Salerno, Italy) where baby leaf crops are cultivated in numerous cycles (up to 5-7) per year. Three sorghum varieties for forage or biomass (Goliath, BMR 201, and BMR 333) were cultivated in two farms at Eboli and San Marzano sul Sarno with the aim of studying their responses in term of fresh and dry aboveground biomass yielded, carbon (C) and nitrogen (N) content of the biomass incorporated in soil, and C balance in amended soils after one year of ordinary cash crop sequences. No differences, with regard to all the parameters measured, were pointed out among the tested varieties in each site. The sorghum cycle lasted 45 days at Eboli, yielding on average 98 and 13 t ha -1 of fresh and dry biomass, respectively; soil biomass incorporation supplied on average 5.8 t ha -1 of organic C and 273 kg ha -1 of total N. In the farm of San Marzano, sorghum cycle lasted 68 days, yielding 116 and 18 t ha -1 of fresh and dry biomass, respectively; soil biomass incorporation supplied on average 8 t ha -1 of organic C and 372 kg ha -1 of total N. After one year, the plots amended with sorghum biomass showed a soil organic carbon (SOC) concentration not different from the starting point, while SOC decreased in fallow plots. At Eboli, initial SOC content was 12.3 g kg -1 , but one year later it resulted 12.3, 12.8, 12.2 and 11.3 g kg -1 in BMR 201, BMR 333, Goliath and control plots, respectively. At San Marzano, initial SOC content was 11.4 g kg -1 , but one year later it resulted 11, 12, 10.7 and 10.5 g kg -1 in BMR 201, BMR 333, Goliath and control plots, respectively. The annual C balance put in evidence that the green manure with sorghum biomass caused SOC losses higher than those detected in fallow plots. This let us suppose a prime effect in boosting the soil microbial C mineralisation. Only cv BMR 333 in the Eboli trial pointed out a positive SOC change of 1.8 t ha -1 . Further studies are requested to better understand the real efficacy of sorghum cover crop in soil amendment under tunnels devoted to intensive vegetable crop sequence.