Isa A. M. Yunusa

Cropping of acid sulfate soils requires effective treatment of their inherently low pH. We evaluated the efficacy of applications of two levels of lime (0 or 2 Mg/ha), two levels of organic fertiliser (0 or 5 Mg/ha), and three levels of biochar (0, 10 or 30 Mg/ha) in a factorial design for ameliorating acidity in an acid sulfate soil, and measured the subsequent growth and yield of baby corn (Zea mays L.). Lime increased soil pH(H2O) from 3.75 to 4.12, salinity from 1.72 to 1.95 dS/m, and cob yield by 30%. None of the amendments significantly altered total organic carbon or total nitrogen concentrations in the soil. Biochar additions increased cob yields by an average of 28% on both unlimed and limed soil. Addition of organic fertiliser increased cob yield by 45% on unlimed soil but had no significant effect on yields on limed soil. The yields obtained with liming were similar to the highest yields achieved with biochar or organic fertiliser applied either separately or in combinations. Overall, cob yields were increased by 19% with addition of organic fertiliser. The yield increseas from additions of biochar or organic fertiliser were associated with improvements in nutrient supply. However, the increases in cob yield were associated with reduced cob protein, probably resulting from poor availability of nitrogen late in the season. We conclude that biochar and organic fertiliser applied in relatively large quantities can be viable treatments for cropping acid sulfate soils.

BACKGROUND: Salinity constrains agricultural sustainability and crops differ in their response. We tested the hypothesis that contrasting responses in canopy and stomatal traits to salinity will cause convergence of water‐use in okra and tomato.RESULTS: Stomata were found almost exclusively (>90%) on the lower leaf surface of tomato, but okra produced ~30% of stomata on the upper leaf surface. While salinity reduced the magnitudes of canopy and stomata traits in tomato, stomata traits were either unaffected or enhanced in okra. Salinity reduced the rates and duration of stomatal conductance (g_s) in both crops, more severely in tomato, in which g_s was restricted to early mornings in contrast to its bell‐shape trend in okra. The superiority of okra in its stomata traits was compensated by the larger plant canopies in tomato, resulting in both daytime canopy transpiration and total plant water‐use within 17% and 28%, respectively, of each other for the two crops. A tight stomatal control of transpiration that minimised use of water and its uptake from the soil conferred a superior salinity tolerance on tomato over okra. In both crops, stomata density (D) was inversely correlated with stomata area (A), while water‐use was positively correlated with plant leaf area, in addition to D and A in tomato; g_s was also correlated with stomata area index in tomato.CONCLUSION: Differences in water‐use for both crops were relatively narrow, despite the several‐fold differences in their canopy and stomata traits. Under saline conditions, irrigation intervals should be long for tomato but short for okra. © 2021 Society of Chemical Industry.

BACKGROUND: Analyses of sensitivity of Global Food Security (FS) score to a key set of supply or demand factors often suggest population and water supply as being the most critical and on which policies tend to focus. To explore other policy options, we characterized the nexus between GFS and a set of supply or demand factors including population, agricultural and industrial water uses, agricultural publications (as a surrogate for investment in agricultural research and development (R&D)) and corruption perception index (CPI), to reveal opportunities for attaining enduring GFS.RESULTS: We found that despite being the primary driver of demand for food, population showed no significant correlation with FS scores. Similarly, agricultural water use was poorly correlated with GFS scores, except in countries where evaporation exceeds precipitation and irrigation is significant. However, FS had a strong positive association with industrial water use as a surrogate for overall industrialization. Recent expansions in cultivated land area failed to yield concomitant improvements in FS score since such expansions have been mostly into marginal lands with low productivity and thus barely compensated for lands retired from cropping in several developed economies. However, FS was positively associated with agricultural R&D investments, as it was with the CPI scores. The apparent and relative strengths of these drivers on FS outcome amongst countries were in the order: industrial water‐use ≈ publication rate ≈ corruption perception ≫ agricultural water use > population.CONCLUSIONS: We suggest that to enshrine enduring food security, policies should prioritize (1) increased R&D investments that address farmer needs and (2) governance mechanisms that promote accountability in both research and production value chains. © 2018 Society of Chemical Industry

As single superphosphate availability decreases due to closure of aging manufacturing plants increasing attention is being paid to alternative phosphorus (P) and sulfur (S) sources. This glasshouse study, conducted under non-leaching conditions was undertaken to evaluate the S supplying capacity of gypsum, S bentonite, elemental S (ES) and a range of P containing fertilizers and those where ES was added as a coating or incorporated. The magnitude of crop response in terms of shoot biomass to applied S fertilizer sources followed the order of sulfates > powdered ES > coated/incorporated ES > S/bentonite. These results indicate that fertilizers containing a mixture of sulfate and micronized ES (<75 µm), either incorporated within the granule or coated onto the fertilizer are agronomically effective. The results also suggest that local S coating of finished fertilizers is a feasible alternative to S incorporation undertaken at a central fertilizer plant.

ISHS XXIX International Horticultural Congress on Horticulture: Symposia of the V World Congress on Medicinal and Aromatic Plants and International Symposium on Plants, as Factories of Natural Substances, Edible and Essential Oils Propagation of Melaleuca cajuputi by stem cuttings on the central coast of Vietnam

Low rainfall is a major limitation to expanding the dairy industry in semi-arid environments in East Africa. In such dry areas, plants need to keep their tissues hydrated and stomata open for carbon exchange and to grow. On this basis, we assessed the productivity of 10 lines of Napier grass (Pennisetum purpureum Schum.), which formed three yield clusters: low yielding (LYC), moderate yielding (MYC), and high yielding (HYC), in a wet highland (Muguga) and semi-arid lowland (Katumani) of Kenya. Stomatal conductance (g_s), leaf water potential (LWP) and relative water content (RWC) were monitored, and water use simulated, over four growth cycles in 2012. These were used with measurements of leaf area index (LAI) and plant dry weight to explore the possible use of these physiological parameters for assessing productivity potential of Napier grass accessions. The plants were less stressed at Muguga, where g_s was 700–1000 mmol m⁻² s⁻¹, LWP −0.4 to −0.9 MPa and RWC was 82–95%; these values at Katumani were 450–750 mmol m⁻² s⁻¹, −0.7 to −1.4 MPa and 74–93%, respectively. Total water use at Katumani was of the order HYC ≈ MYC (390 mm) > LYC (370 mm), and water use efficiency (WUE, kg ha⁻¹ mm⁻¹) followed the same order HYC (34.3) > MYC (32.6) > LYC (24.9); whereas at Muguga water use averaged 710 mm for HYC and MYC, greater than 676 mm for LYC, and WUE (kg ha⁻¹ mm⁻¹) averaged 29.2 for HYC and MYC, and 19.4 for LYC. The three water stress indices were poor, whereas vigorous early canopy development (determined as LAI) was a more reliable predictor of productivity potential of Napier grasses. In these dry environments, therefore, early rapid canopy development can be an effective indicator of yield potential and a credible selection criterion. © 2016 Society of Chemical Industry

SUMMARY: Ten accessions of Napier grass (Pennisetum purpureum Schumach.) were evaluated for their dry matter (DM) yield and forage quality in a semi-arid lowland (Katumani) and a relatively wet highland (Muguga) over seven growth cycles from 2011 to 2013 in tropical Kenya. Three biomass yield clusters were identified from the 10 accessions as high-yielding (HYC), medium-yielding (MYC) and low-yielding (LYC) clusters for both sites. Total biomass (shoot and root) yields (t ha⁻¹) over the seven growth cycles were 25.3 for HYC, 22.2 for MYC and 19.6 for LYC at Katumani and 40.0, 41.4 and 29.1 at Muguga. Total biomass yield averaged over the study period was DM 22.4 t ha⁻¹ at Katumani and 36.8 at Muguga. Rainfall productivity was higher at Katumani (28.8 kg ha⁻¹ mm⁻¹) than 20.8 kg ha⁻¹ mm⁻¹ at Muguga. Neutral detergent fibre (NDF) was lower in LYC, which was more leafy than the other clusters and there was little difference in NDF between the two sites.

Following a field campaign to determine the species composition, canopy cover, aboveground annual production and leaf area index (LAI) of the semi-arid savanna of north-western Namibia, we present ...