## 3 Results
### Crop Yield, Irrigation Amount, and Water Productivity in the Experimental Field  
Table 2 shows the results of the first cropping season. The production of tomatoes in the \(-25\) kPa-controlled automatic irrigation plot was the highest at 8178 kg/10a (10a = 1000 m\({}^{2}\)), followed by 7147 kg/10a in the \(-33\) kPa-controlled automatic irrigation plot and 6577 kg/10a in the empirical manual irrigation plot [20]. The largest amount of water was irrigated--323.6 m\({}^{3}\)/10a--in the \(-25\) kPa-controlled automatic irrigation plot and the smallest amount of water was irrigated--264.0 m\({}^{3}\)/10a--in the \(-33\) kPa-controlled automatic irrigation plot. The ratio of the crop yield was 108.7% in the \(-33\) kPa-controlled automatic irrigation plot and 124.3% in the \(-25\) kPa-controlled automatic irrigation plot compared with the empirical manual irrigation plot. Furthermore, the ratio of the water consumption in the \(-33\) kPa-controlled automatic irrigation plot was lower at 95.5% and the \(-25\) kPa-controlled automatic irrigation plot was higher at 117.1%. Water productivity determined the efficient use of water by the crop yield per cubic meter of water consumption [27]. It was 23.8 kg/m\({}^{3}\) for the empirical manual irrigation plot, 27.1 kg/m\({}^{3}\) for the \(-33\) kPa-controlled automatic irrigation plot, and 25.3 kg/m\({}^{3}\) for the \(-25\) kPa-controlled automatic irrigation plot, among which the \(-33\) kPa-controlled automatic irrigation plot showed the highest results. The \(-25\) kPa-controlled automatic irrigation plot produced more crops than the \(-33\) kPa-controlled automatic irrigation plot, but the water consumption was also higher. Therefore, the \(-33\) kPa-controlled automatic irrigation plot had the most efficient use of water.  
Table 3 shows the results of the second cropping season with minimal irrigation on the \(-33\) kPa-controlled automatic irrigation plot to increase the water productivity. The tomato yield of 3879 kg/10a in the \(-33\) kPa-controlled automatic irrigation plot was higher than the tomato yield of 3826 kg/10a in the empirical manual irrigation plot [20]. The empirical manual irrigation plot was irrigated with 75.36 m\({}^{3}\)/10a of water and the \(-33\) kPa-controlled automatic irrigation plot was irrigated with 65.04 m\({}^{3}\)/10a of water, so the empirical manual irrigation plot was irrigated with more water. The ratio of the crop yield was 101.4% in the \(-33\) kPa-controlled automatic irrigation plot compared with the empirical manual irrigation plot. Furthermore, the ratio of water consumption in the \(-33\) kPa-controlled automatic irrigation plot was 86.3% compared with the empirical manual irrigation plot. The water productivity was 50.8 kg/m\({}^{3}\) for the empirical manual irrigation plot and 59.6 kg/m\({}^{3}\) for the \(-33\) kPa-controlled automatic irrigation plot, among which the \(-33\) kPa-controlled automatic irrigation plot showed the higher result. Therefore, the \(-33\) kPa-controlled automatic irrigation plot had the more efficient use of water.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Plot**} & **Crop Yield** & **Irrigation** & **Ratio of Empirical Manual Irrigation Plot (\%)** & **Water Productivity** \\  & **(kg/10a)** & **Amount (m\({}^{3}\)/10a)** & **Crop Yield** & **Irrigation Amount** & **(kg/m\({}^{3}\))** \\ \hline Empirical manual irrigation & 6577 & 276.4 & 100 & 100 & 23.8 \\ \hline \(-33\) kPa automatic irrigation & 7147 & 264.0 & 108.7 & 95.5 & 27.1 \\ \hline \(-25\) kPa automatic irrigation & 8178 & 323.6 & 124.3 & 117.1 & 25.3 \\ \hline \end{tabular}
\end{table}
Table 2: Crop yield, irrigation amount, and water productivity by each plot in the first cropping season.