Società Italiana di Agronomia XLVII Convegno Nazionale
L'Agronomia nelle nuove Agriculturae Marsala (TP), 12-14 settembre 2018
Use Of Biodegradable Films For Solarization: Effects On Temperature, Moisture And N-NO3 And N-NH4 Content Of Soil Eugenio Cozzolino1, Ida Di Mola2, Lucia Ottaiano2, Luigi Giuseppe Duri2, Vincenzo Leone1, Sabrina Nocerino2, Roberto Maiello2, Vincenzo Cenvinzo2, Mauro Mori2 1CREA-Research
Centre for Cereal and Industrial Crops, 81100 Caserta, eugenio.cozzolino@crea.gov.it 2 Dip. di Agraria, Univ. “Federico II” Napoli, IT
Introduction The solarization is a no-chemical method that is largely used in many temperate regions for soil disinfestation such as pathogens (fungi, bacteria, nematodes) and weeds control. Soil solarization is usually made covering soil with transparent plastic film for 4-6 weeks with the aim to increase soil temperature. But the solarization has also other secondary effects such as the increase of ammonium- and nitratenitrogen concentrations. Currently soil solarization is usually made with plastic films like polyethylene, but they have a great limit. Therefore the use of biodegradable films could allow to overcome these problems because they, after solarization, degrade progressively in the soil. However, it is need to verify if the biodegradable film can obtain the same performance of plastic film in terms of soil disinfestation (data not showed) and so in terms of temperature increase. Aims: to evaluate the possible effects of these films on moisture and some chemical proprieties of soil (N-NO3 and N-NH4 concentrations).
Materials and Methods The experiment was carried out in the summer 2017 at experimental field of Department of Agriculture, in Portici (NA) in a polyethylene greenhouse. A completely randomized block design with 3 replicates was used to compare 2 different mulching films for solarization: the traditional transparent low density polyethylene (LDPE with 60µ thickness) and the transparent biodegradable film-PC17T6/35 (BIO with 35µ thickness). They were compared with bare soil (control). The films were manually placed on 22 June 2017; at the same time the temperature probes, three per treatment, were installed for measuring continuously the soil temperature at depth: 0-15 cm. The films were removed after one month, but the trial lasted two months for monitoring the trend of chemical soil proprieties also in the first month successive to films removal. Physical and chemical soil properties (0-15 cm): sandy loam soil (USDA classification); pH=6.94; EC=0.6 dS m-1; O.M.=2.2%; P=87 ppm; K=1800 ppm and N=0.12%. Every 15 days, a soil sample per treatment and replicate were made to determinate water content and N (N-NO3 and N-NH4) content.
Results Fig.1a: First month, the air max temperature under the greenhouse Fig. 3: During the two test months the soil moisture had a decreasing was on average 19°C higher than external temperature (54.7 vs trend and the control showed the lower values (8.6% vs 10.8% 45.7°C respectively) with a peak of 61.4°C. The temperature of two average value of cover films) at the last sampling. covered soils was about 7°C higher than control soil, but there were not differences between them (average value was 46.2 and 45.7°C for LDPE and BIO, respectively). Fig.1b: The min temperature, the LDPE showed the best performance with almost 2°C and 5.6°C more than BIO and control respectively. Tab.1: The soil temperatures have been grouped in 4 ranges (36-40, 41-45, 46-50, 51-55°C) and per each ranges the number of hours have been calculated. Both cover films showed obviously a greater Fig 1. Trend of maximum (a) and minimum (b) temperature during the test period. number of warmth hours than control in the all ranges with the LDPE higher than BIO: the total hours higher than 36°C were 537 and 476 respectively. The control showed only 228 hrs with soil temperature higher than 36°C. Fig.2a: The N-NO3 increased until the removal of films, then it decreased, but the BIO values was always higher. Fig.2b: The N-NH4 was about constant in the soil control, it had a peak in the two films at day 15, higher in LDPE, then it was stable Fig. 2 Trend of nitrate (a) and ammonia nitrogen (b) during the test period. for BIO and decreased for LDPE, that reached final BIO value. Table 1. Number of hours per each treatment respect to 4 ranges of temperatures during the solarization. T ranges °C 36-40 41-45 46-50 51-55
Control 192 36 0 0
LDPE n° hours 214 188 114 21
BIO 209 139 120 8
Fig. 3 Trend of soil moisture during the test period.
Conclusions The biodegradable film would seem suitable for solarization, because it has a behavior similar to LDPE but, being more porous than that, it allows a greater activity of aerobic bacteria with a greater NO3 production.