## 2 Materials and Methods  
The research was carried out in 2013 on two sites in the Moscow region and in the Kursk region of Russia. The first site (the Moscow site) was situated at the Precision Farming Experimental Field of the Russian Timiryazev State Agricultural University (RTSAU: 55\({}^{\circ}\)50\({}^{\prime}\)14\({}^{\prime\prime}\) N, 37\({}^{\circ}\)33\({}^{\prime}\)56\({}^{\prime\prime}\) E), situated in Moscow, Russia. This area belongs to the climate zone of south taiga. The experimental site has a temperate and continental climate with distinctive seasons. The mean annual temperature is 3.8 \({}^{\circ}\)C, with minimum and maximum mean temperatures of \(-\)6 \({}^{\circ}\)C in January and 18.5 \({}^{\circ}\)C in July, respectively. The growing season shows an average daily temperature greater than 5 \({}^{\circ}\)C and typically lasts for 175 days. The average annual precipitation is 550-650 mm: two-thirds of the precipitation is in the form of rain and one third is in the form of snow. Nearly 40% of the precipitation falls during the cold period between November and March, and the other 60% falls during April to October. The soil type is Umbric Albeluvisols (arable sod-podzolic soils under Russian soil classification), and the topsoil texture is mainly sandy loam. Arable sod-podzolic soils have around 1% SOC, 5.4 pH (KCl) and NPK medium-enhanced contents. The natural vegetation in this area consists of mixed forests of the temperate climate. The second site (the Kursk site) was located on a farmer's agricultural field near the urban settlement of Pristen (51\({}^{\circ}\)8\({}^{\prime}\)44\({}^{\prime\prime}\) N, 36\({}^{\circ}\)30\({}^{\prime}\)22\({}^{\prime\prime}\) E), located in the Kursk region of Russia. The Kursk site is situated in south of the Moscow site at a distance of about 600 km. The area belongs to the climate zone of forest-steppe. The second experimental also site has a temperate and continental climate with distinctive seasons. The mean annual temperature is much higher (4.6 \({}^{\circ}\)C), with minimum and maximum mean temperatures of \(-\)6 \({}^{\circ}\)C in January and 20.5 \({}^{\circ}\)C in July, respectively. The growing season lasts for 196 days: from 7 April to 22 October. The average annual precipitation is approximately the same: 550-600 mm. The distribution of precipitations is about the same as in the Moscow region, but long dry periods are common in the summer. The soil type is Chernozems Luvic (arable leached deep chernozems on loess-like loam under Russian soil classification), and the topsoil texture is mainly clay loam. Chernozems are very fertile soils: in this region they have 3.6-3.8% SOC, 5.5-6.0 pH (H\({}_{2}\)O) and NPK high-enhanced contents. The natural vegetation in this area consists of forb meadow-steppe associations and deciduous forests in the beams. The total field areas at the Moscow and Kursk sites were 1.55 and 80.84 ha, respectively. The two barley crop fields are characterized by different climate conditions, but they also represent differences in agronomic practices. The Moscow field was used for barley planting (_Hordeum vulgare_ L., breed Mihailovsky). Sowing was in early May 2013 and harvest was on 14 August. The field was treated with a 0.4 kg/ha herbicide mix (florasulam and 2,4-D as the ethylhexyl ester) on 25 May. The yield was estimated on 8 study plots (50 m \(\times\) 25 m) evenly distributed over the field, which were harvested by combine harvester. Grain yield varied from 3.67 to 4.48 tons per ha, and was, on average, 4.08 tons per ha. This high yield reflects the fact that the field in the Moscow region was cultivated using intensive technology with fertilizers and herbicides. The Kursk field was also used for barley planting (_Hordeum vulgare_ L., breeding line Xanadu). Sowing was on 25 April and harvest was between 14 and 19 August. The Kursk field is cultivated by a small farmer, whose target is profit, so he is interested in maximum yield at minimum cost.