## 2 Materials and Methods  
### Experimental Set-Up and Pedo-Climatic Conditions  
The trial was carried out in 2015 and 2016 at the Experimental farm of the Council for Agricultural Research and Economics (Research Centre for Agriculture and Environment), in southern Italy (Rutigliano, lat.: 40\({}^{\circ}\)59\({}^{\prime}\) N, long.: 17\({}^{\circ}\)01\({}^{\prime}\) E, alt.: 147 m asl) on 3-year-old peach (_Prunus persica_ (L.[PERSON] var. _Iaevis_) trees of a late ripening cultivar \"Calred\" [32] grafted on Missouri rootstock, trained as slender spindle and spaced \(4.0\times 2.5\) m. The experimental site is under the Mediterranean climate, characterized by warm and dry summers. The average air temperature throughout the year and during the vegetative-reproductive season is 15.5 and 20 \({}^{\circ}\)C, respectively, and the annual rainfall is about 535 mm, mainly concentrated in the autumn and late winter periods and usually greatly reduced, or absent, in the spring-summer period [33].  
Four different orchard managements were tested: soil tilled (T); inter-row mulching with a reusable and machine-resistant reflective plastic film (C/820 Black Silver Orchard; thickness: 100 \(\upmu\)m; Ginegar Plastic product Ltd., Ginegar, Israel) to reduce soil evaporation and to increase the diffuse light (M); inter-row mulching with horse bean (_Vicia faba_. L.) sown in November and flattened after peach fruit set forming a natural mulching on the soil (F). The last treatment (S) was established on tilled soil supplying the same irrigation volume of M that was supposed to be lower than the control (T) as evaporation was limited by the plastic mulching. Since horse bean contributed to Nitrogen fixation, N supply on F treatment was halved in comparison to T, M and S, while the Phosphorus and Potassium supply was increased by 25% in order to feed the service crop.  
In order to verify the homogeneity of soil characteristics at the beginning of the trial, as well as to evaluate the evolution of the soil conditions as a function of the four treatments, three soil samples per treatment were collected at the beginning of the trial (before flattening period), after the harvest of the first year and at the end of the second year (just before the winter pruning). Soil was evaluated for its physico-chemical traits: soil texture by hydrometer method, total carbon organic content (TOC, %) by the dry-combustion procedure with a TOC Vario Select analyzer (Elementar, Germany), pH, electric conductibility (EC, dS m\({}^{-1}\)), N (g kg\({}^{-1}\), [PERSON] procedure) and P (mg kg\({}^{-1}\), [PERSON] method) content. Soil texture was similar among the four treatment and it was classified as clay loam [34]. Soil water content in volume at field capacity (FC, \(-0.03\) MPa) and wilting point (WP, \(-1.5\) MPa) were \(0.34\) m\({}^{3}\) m\({}^{-3}\) and \(0.21\) m\({}^{3}\) m\({}^{-3}\), respectively (measured using the Richards chambers). At 0.6 m of depth, the parent rock is present; this reduces the capacity of the root systems to expand beyond this layer. At the beginning of the trial also, the evaluated chemical trait results were not statistically different among the treatments (Table 1).