In-Field Rainwater Harvesting Tillage in Semi-Arid Ecosystems: I Maize-Bean Intercrop Performance and Productivity

The purpose of this study was to monitor and compare the growth and productivity of maize/beans sole and inter-cropping systems under conventional (CON) and in-field rainwater harvesting (IRWH) tillage practices. During the typical drought conditions of the 2018/19 growing season, seven homestead gardens of smallholder farmers (four in Paradys and three in Morago villages) in the Thaba Nchu rural communities of South Africa were selected for on-farm demonstration trials. Two tillage systems CON and IRWH as the main plot and three cropping systems as sub-treatment (sole maize and beans and intercropping) were used to measure crop growth and productivity parameters. The results showed that IRWH tillage had significantly higher above-ground dry matter for both sole maize (29%) and intercropped maize (27%) compared to CON treatments. The grain yield under both tillage systems showed that IRWH-Sole >> IRWH-Ic >> CON-Sole >> CON-Ic, with values ranging from 878.2 kg ha-1 to 618 kg ha-1 (p ≤ 0.05). The low harvest index values (0.21-0.38) could have been due to the effect of the drought during the growing season. The results of precipitation use efficiency (PUE) showed that the IRWH tillage was more effective at converting rainwater into maize biomass and grain yield compared to CON tillage. However, the different cropping systems did not show a consistent trend in PUE. During the growing season, the PUE for AGDM varied for different tillage and cropping system treatments in Morago and Paradys. For maize, it ranged between 10.01-6.07 and 9.93-7.67 kg ha-1, while for beans, it ranged between 7.36-3.95 and 7.07-3.89 kg ha-1 mm-1. The PUE for grain yield showed similar trends with the significantly highest values of PUE under IRWH tillage systems for the Morago sites, but there were no significant differences at the Paradys site in both tillage and cropping systems. There is a critical need, therefore, to devise alternative techniques to promote an increase in smallholders' productivity based on an improved ability to capture and use resources more efficiently.

Relay intercropping of maize with common dry beans to rationalize nitrogen fertilizer

Maize (Zea mays L.) and dry beans (Phaseolus vulgaris L.) are important staple food and cash crops worldwide. Common bean in an intercrop with maize contributes to biological nitrogen fixation, which stabilize productivity of cropping systems and reduce negative environmental impacts and loss of biodiversity for sustainable agriculture. A field experiments was performed during the years of 2020 and 2021 at Sers El-Layian Station, northern Egypt. The current study aiming to study the effect of three sowing dates of maize, represent 3 co-growth duration [T1: at flowering stage (FS) of common beans (60 days co-growth duration), T2: 15 days after FS (45 days co-growth duration), and T3: 30 days after FS (30 days co-growth duration with beans)] and three N fertilizer levels (N1: 190.4, N2: 238.0, and N3: 285.6 kg N/ha of maize) on productivity, profitability and N fertilizer rationalization. The longest co-growth duration of maize intercropping with common beans (T1) significantly (P ≤ 0.05) decreased common beans and maize yields compared with T2 and T3. Performance of common beans did not show (P ≤ 0.05) any variation under different N fertilizer levels of maize. Significant (P ≤ 0.05) increase in maize yield and its components with raising N fertilizer level up to N3. Although there was no significant variation in maize yield when applied N2 and N3, however, nitrogen use efficiency (NUE) was significant (P ≤ 0.05) higher in N2 than N3 by 18.34%. Regardless of planting time and N fertilizer level of maize, combined productivity of common beans and maize increased in the intercropped system as cleared by higher total land equivalent ratios (LER) and area time equivalent ratios (ATER). Highest LER value 1.99 was observed at the shortest co-growth period T3 under N3 followed by 1.97 with N2. Positive values in the actual yield loss index (AYL) indicated intercropping advantage. Different competition indices showed a greater dominance of maize over common beans (aggressivity, Ag; competitive ratio, CR; actual yield losses, AYL). However, the intercropping systems increased the economic advantage (intercropping advantage index, IAI and monetary advantage index MAI) over monoculture. These results imply that shortening the period of co-growth maize with common beans (T3) and applying 238.0 kg N/ha in the relay intercropping system reduced mineral N fertilizer use by 16.67% compared to the advised level 285.6 kg N/ha along with increased productivity per unit area and economic advantages for small-farmer.