*3.1. Rainfall Variability*

Rainfall data revealed a high inter-seasonal variability of rainfall (i.e., 17%) and frequent dry spells lasting for 2–16 days (Figure 5). From 1998 to 2014, the frequency of dry spells in Vea and Bongo ranged between 18 and 28 occurrences. Furthermore, the analysis indicated increasing intra-seasonal rainfall variability in both schemes during the observation period, most likely due to climate change.

**Figure 5.** Total annual rainfall and frequency of dry spells (FDS) in the Vea and Bongo irrigation schemes during the years 1998–2014.

### *3.2. Crop Growth Parameters*

The PD of maize ranged between 4.1 and 5.5 plants m−<sup>2</sup> across the schemes (Table 3). The decline in the maize aboveground DM in VF1 and BNF1 in the VIS was attributed to the effects of late planting (i.e., 3 July, 2014) and waterlogging, respectively (Figure 6a). The PD of tomato was generally higher in the BIS (3.3–3.5 plants m−<sup>2</sup> in 2014–2015, and 3.6–4.2 plants m−<sup>2</sup> in 2015–2016) than in the VIS (2.6 plants m−<sup>2</sup> in 2014–2015, and 3.3–3.5 plants m−<sup>2</sup> in 2015–2016) (Table 3). The difference was partly due to the narrower inter-row spacing observed in the BIS (0.28–0.35 m) compared to that in the VIS (0.25–0.54 m). The remarkably low tomato DM in the Vea BNF1 field in 2014–2015 was due to the impact of plant root disease (Figure 6b).


**Table 3.** Crop growth and yield components in the Bongo and Vea irrigation schemes during the 2014–2016 observation period.

n.d. = not determined/applicable.

**Figure 6.** Aboveground dry matter of (**a**) maize in 2014; (**b**) tomato in 2014–2015 and (**c**) tomato in 2015–2016 in the Bongo and Vea irrigation schemes.

The higher tomato DM observed in the 2015–2016 dry season compared to the previous dry season could be due to excessive field-level water application in that season, when an increased water availability was recorded (Figure 6b,c). The downward trend of the LAI of tomato observed in the BIS

in 2014–2015 might be due to an insufficient water supply in the later part of the dry season. In contrast, the upward trend of the LAI in the VIS reflects an adequate water supply (Figure 7). The maximum RD of tomato and maize ranged between 0.28 and 0.37 m (Table 1), a result of the shallow soil depth, not exceeding 0.4 m in the UER.

**Figure 7.** Leaf area index of tomato during the 2014–2015 dry season in the (**a**) Bongo and (**b**) Vea irrigation schemes.
