L. R. Hossner

Variable sorghum growth in acid soils of subhumid West Africa

Abstract A sequence of experiments was conducted to define soil chemical properties associated with poor early growth of sorghum [Sorghum bicolor (L.) Moench] in selected Grossarenic and Plinthic Paleustalfs or Eutric Nitosols (FAO Legend) of subhumid West Africa. Millet [Pennisetum americanum (L.) K. Schum] appears to be tolerant to the soil problem under study. This soil constraint appears to inhibit sorghum growth and yield in all the soil positions of the toposequence of the Cinzana station (Mali), the toeslope excepted. Application of urea (100 mg N kg‐1 of soil) or liming followed by an N application neither prevented symptoms of poor growth nor significantly increased dry matter yield (DMY). However, application of P alone or any treatment combination containing P resulted in improved sorghum growth and yield. DMY was strongly correlated with Bray‐1 P (r = 0.74**). Exchangeable soil Al had a significant but negative impact on DMY (r = ‐0.42**). Amending the soil with Tilemsi rock phosphate (RP) or ...

Variability in pearl millet (Pennisetum americanum) fields in semiarid West Africa

Abstract Extreme variability in pearl millet [Pennisetum americanum (L.) K. Schum] growth over very short (2–20 m) distances in the poorly buffered sandy soils of the semiarid West African Sahel poses major limitations to millet production and to field research efforts. A pot study using soils taken at 26 sites along a 15‐m transect from an unproductive to a productive region in a research field was conducted to determine the causes of variability in millet growth. Plant analyses showed that millet‐shoot weight 37 days after planting correlated best with shoot Al concentration (R2 = 0.81 for the 22 most unproductive sites). The critical concentration for Al toxicity in millet shoots was approximately 600 μg g−1. Millet growth also correlated well with shoot K concentration (R2 = 0.53). Poorly growing plants had deficient concentrations of P and K and potentially toxic levels of Mn. Low concentrations of plant P may be related to P fixation by soil Al.

Sorghum growth in acid soils of West Africa: Variations in soil chemical properties

Three field experiments were conducted to alleviate soil chemical properties associated with poor early growth of sorghum [Sorghum bicolor (L) Moench] in selected Grossarenic and Plinthic Paleustalfs or Eutric Nitosols of subhumid West Africa. These experiments were implemented for two growing seasons on the same plots. Soil amendments used (lime, manure, Tilemsi phosphate rock, and water‐soluble P source) significantly increased soil pH (5.1–7.8), decreased exchangeable Al3+ (0.48–0 cmolckg−1), and increased Bray‐1 P content (7.1–48.5 mg kg−1), organic C content (0.19–0.51), and ECEC (1.30–3.10 cmolc kg−1). The net effects of such improvements were excellent sorghum growth and yield in the first growing season. However, most sorghum seedlings failed to grow in the second growing season. Affected sorghum seedlings had deficient contents of P (<2 g kg−1) and Al contents higher (more than twofold) than the toxic level of 500 mg Al kg−1. These suggest that P deficiency and Al toxicity may be associated with ...

A comparison of extraction methods for evaluating Fe and P in flooded rice soils

Poorly crystalline Fe in soil has been shown to affect Fe and P availability. Oxalate extractable Fe, a measure of poorly crystalline Fe oxides, has not been compared to soil test methods for Fe and P in rice soils. Twenty eight soils used for rice production were incubated under aerobic and anaerobic soil conditions and extracted for Fe and P with ammonium oxalate, ammonium acetate-EDTA (AA-EDTA), ammonium bicarbonate-DTPA (ABDTPA) and DTPA. Citrate-dithionite extractable Fe and Fe content of rice plants in a greenhouse experiment were also determined. Soils used in this experiment had a large amount of poorly-crystalline Fe oxide. In some soils, poorly-crystalline Fe constituted 60% of the citrate-dithionite extractable Fe. The amount of extractable Fe and P increased significantly under anaerobic conditions. The relationships between extractants showed that DTPA Fe was highly correlated to AB-DTPA Fe and oxalate Fe was highly correlated to AA-EDTA Fe. There was no relationship between Fe and P extracted by AB-DTPA, while there was a better relationship with ammonium oxalate and AA-EDTA extractants. Poorly-crystalline Fe and P extracted by ammonium oxalate were correlated.

Effect of Diamou Lime, Gypsum, and Tilemsi Phosphate Rock on Acid Soils of the Sudano-Sahelian Region of Mali

Continuous cropping, use of chemical fertilizers, and lack of sound soil management practices on poorly buffered kaolinitic Alfisols of the Sahel have accelerated soil acidity and reduced exchangeable Ca and crop yield. This study was conducted at the Cinzana Experiment Station in Mali, to determine the relative importance of Ca and P for millet grown on Plinthustalf sandy and Haplustet clayey soils for three years. The soils selected had very low to medium Bray P1 and extractable Ca concentrations. Three local sources of Ca and one source of P, Diamou lime, gypsum, and Tilemsi phosphate rock (TPR) were surface applied at lime application(LA) of 0, 0.5, 1.0, and 2.0 CaCO3equivalent. Among the three Ca sources, Diamou lime increased pH and exchangeable Ca concentration of surface soil, TPR increased the Ca concentration in the surface soil, and gypsum increased the Ca concentration of both surface and subsurface soil, but like TPR had no effect on soil surface or subsurface pH. The degree of millet yield response to Ca source varied with soil and year. No response to Ca was observed in a low rainfall year, but a positive response to TPR occurred in all three years, regardless of rainfall. For the soils studied, TPR can be considered a good local source of Ca and P, with potential to reduce Al toxicity and/or Ca deficiency. In general, application of P was more critical than Ca for millet growth in these soils.