## Materials and Methods
### Experimental Design and Farm Management  
The soil was clay/loam texture and contained 3.82 g\(\cdot\)kg\({}^{-1}\) organic matter, 0.64 g\(\cdot\)kg\({}^{-1}\) total N, 11.75 mg\(\cdot\)kg\({}^{-1}\) available phosphorus (P), and 182.31 mg\(\cdot\)kg\({}^{-1}\) available potassium (K) in the 0-20-cm soil layer [27; 28; 29]. Organic matter content of the soil was low (<0.5%) at the initiation of the experiment [30]. The study site was left uncultivated for three years prior the experiments. A randomized complete blocked design with four replications was adopted based on a split plot arrangement. Main plot size \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline  & \multicolumn{2}{c}{**Temperature (\({}^{\circ}\)C)**} & \multicolumn{2}{c}{**Evaporation (mm)**} & \multicolumn{2}{c}{**Relative Humidity (\%)**} & \multicolumn{2}{c}{**Precipitation (mm)**} \\ \cline{2-9}  & **2015** & **2016** & **2015** & **2016** & **2015** & **2016** & **2015** & **2016** \\ \hline March & 3.6 & 3.4 & 53.62 & 42.36 & 56.32 & 61.32 & 19.62 & 35.62 \\ April & 7.4 & 6.4 & 71.40 & 61.35 & 45.30 & 50.57 & 24.32 & 24.36 \\ May & 10.8 & 9.8 & 90.35 & 84.35 & 42.68 & 46.35 & 15.35 & 17.65 \\ June & 17.1 & 16.5 & 113.62 & 117.89 & 41.28 & 36.32 & 8.65 & 16.32 \\ July & 19.2 & 18.1 & 120.36 & 132.57 & 37.36 & 29.64 & 6.62 & 8.65 \\ August & 25.6 & 24.3 & 154.40 & 160.32 & 30.17 & 31.64 & 0 & 1.3 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Monthly average evaporation, relative humidity, temperature, and precipitation of Kharajo region during growing seasons of sunflower. was set to 40 m \(\times\) 6 m and sub-plot size was set to 6 m \(\times\) 6 m. Sunflower (cv. Azargol) was cultivated in a particular site during the wet season (April-August) for two successive years. Two tillage systems, namely, (a) moldboard ploughing (into an average depth of 30 cm) + two shallow disc narrowing (herein referred to as conventional tillage: CT), and (b) chisel ploughing + disc (herein referred to as reduced tillage: RT), were implemented onto the main plots. The subplots were allocated to five fertilizer treatments including F1: control (no fertilizer application), F2: FYM (20 Mg\(\cdot\)ha\({}^{-1}\)), F3: FYM (40 Mg\(\cdot\)ha\({}^{-1}\)), F4: FYM (20 Mg\(\cdot\)ha\({}^{-1}\)) + 50% of the recommended dose of chemical 100 kg\(\cdot\)ha\({}^{-1}\) N + 50 kg\(\cdot\)ha\({}^{-1}\) P + 50 kg\(\cdot\)ha\({}^{-1}\) K, and F5: full recommended dose of chemical fertilizers (100:50:50, that is, 200 kg\(\cdot\)ha\({}^{-1}\) N + 100\(\cdot\)kg ha\({}^{-1}\) P + 100 kg\(\cdot\)ha\({}^{-1}\) K). Farmyard manure was applied annually, and tillage operations were performed every March. Planting dates were 10 April 2015 and 15 April 2016. Sunflower seeds were sown manually in rows 0.75 m apart with a plant-to-plant distance in the row of 0.20 m. This resulted in a plant density of approximately 5-7 m\({}^{-2}\). Dates of harvesting were 21 August 2015 and 14 August 2016. Chemical fertilizers were added after layout preparation in the form of urea (CH\({}_{4}\)N\({}_{2}\)O, N 46%), triple superphosphate (Ca(H\({}_{2}\)PO\({}_{4}\))\({}_{2}\)\(\cdot\)H\({}_{2}\)O), and potassium sulfate (K\({}_{2}\)SO\({}_{4}\)). Each year, farmyard manure was applied, and a tillage operation was performed in March. Then, the planting phase was undertaken a month after the tillage manure application by planting sunflower seeds manually along rows of 75-cm row spacing, at a plant-to-plant distance of 20 cm. Chemical fertilizers were used in three splits including 1/3 N + full P + full K as basal, 1/3 N as top dressing at the vegetative stage (V4), and 1/3 N as top dressing at the reproductive stage (R2). Each year, following tillage operation, the surface layer of the soil was provided with decayed farmyard manure and mixed to a depth of 15 cm by spade to achieve a uniform mix. In order to arrange the experimental plots into ridges and furrows, soil was piled on either side of rows, so that inter-row areas defined the furrows.