Wie wirken "effektive Mikroorganismen" auf EM-Bokashi in der Bananenproduktion (Musa ssp.)?

In Costa Rica, ‘effective microorganisms’ (EM) are used to produce organic fertiliser in the form of Bokashi. This study aimed at investigating the effects of EM addition on the decomposition of banana residues during Bokashi production in comparison to different non-EM control variants (Bokashi produced with: W= water, M= molasses as an EM additive, EMst= sterilized EM). Furthermore, the effects of the above mentioned Bokashi variants on the growth of young banana plants and their effects on the secondary root growth of adult banana plants were evaluated. In comparison to non-EM controls, no increasing effects of EM on the N-mineralization of banana material were observed. All nutrient concentrations were similar for all treatments as well as the weight loss of approximately 77.9 %. The ergosterol concentration was significantly highest in EM Bokashi (77 µg g-1 dry soil), whereas it was lowest in EMst (29 µg g-1 dry soil). Application of all Bokashi variants significantly increased shoot growth of young banana plants under greenhouse conditions compared to a control grown in unamended soil. EM Bokashi and Bokashi produced with molasses significantly decreased the number of root nematodes under greenhouse conditions if compared to the control (nematodes per 100 g: C = 254; W = 143; EMst = 143; M = 67; EM = 38). Furthermore, EM Bokashi increased secondary root growth of adult banana plants in the field (186.7 g) compared to non-composted fresh banana leaves (134.6 g) and a control without mulch application (147 g)

Effect of NaCl Salinity on Growth and Mineral Composition of Ziziphus spina-christi (L.) Willd.

Ziziphus spina-christi (L.) Willd. is a fruit tree species growing wild in arid and semi-arid areas of Asia and Africa where rural populations intensively use its fruits, leaves, bark and wood. However, little is known about the effects of salinity, a widespread problem in these regions, on early growth and mineral composition of this species. This study was conducted under controlled conditions to contribute to filling this gap. Six weeks old seedlings of Z. spina-christi germinated in a full strength Hoagland solution were subjected to 0, 40, 80 and 160 mM NaCl. Compared to the unstressed control salinity levels of 80 and 160 mM reduced plant height, leaf number, leaf chlorophyll, total leaf area and dry matter by 50%. Salinity levels of 40, 80 and 160 mM enhanced leaf water contents by 14, 16 and 17%, respectively and 160 mM NaCl raised the concentration of Na and Cl ions in leaf tissues 81- and 21-fold. The K/Na ratio, in contrast, was hardly affected by increasing salinity indicating adaptation or tolerance of Z. spina-christi to low or moderate NaCl salinity. These results suggest that Z. spina-christi could be an interesting species for re-vegetation of moderately degraded saline lands

Estimation of spatial variability in pearl millet growth with non-destructive methods

Growth variability in pearl millet (Pennisetum glaucum) over short distances is a severe constraint on the interpretation of agricultural experiments in the West African Sahel. The purpose of this study, therefore, was to compare different non-destructive methods to estimate, spatially, millet growth and final yields. Aerial photography, georeferenced radiometric measurements and a chlorophyll meter were tested during three rainy seasons (1996-98) in a nitrogen rate × density × genotype experiment in western Niger. For the radiometric measurements, normalized difference vegetation indices (NDVI) obtained and calibrated for individual millet hills spaced 1.5 m apart were aggregated for the entire experiment with 6000 samples per hectare. A simple calibration procedure was used to correct for variation in soil background reflectance and incident light. For NDVI measurements of individual planting hills, the correlation between plant total dry matter (TDM), leaf weight, leaf area and NDVI was high (r2=0.89-0.91) and regression parameters were genotype-specific. Aggregated georeferenced NDVI measurements at the plot level correlated with grain and TDM at harvest (r2=0.40-0.87). The analysis of true-colour and infrared aerial photographs permitted the monitoring of millet growth and the quantitative evaluation of treatment responses throughout the growing season. The infrared images were the most efficient in the detection of vegetation followed by the normalized green band of true-colour images. The red band was the least effective because of the influence of soil albedo and image vignetting. Although chlorophyll meter measurements reflected relative differences in plant nitrogen status between treatments, their interpretation required destructive sampling and proved unsuitable to predict millet yields. The results demonstrate the potential of georeferenced radiometric data and aerial photographs to improve soil sampling strategies, sequential plant growth monitoring and the statistical design and analysis of experiments. By providing intermediate data sets, the tested tools can also help in the upscaling of ground truth to satellite data in yield prediction studies

Aerial photography to determine fertiliser effects on pearl millet and Guiera senegalensis growth

Variability in plant growth is high on most sandy soils of the West African Sahel, often requiring extensive destructive sampling for the reliable estimation of treatment effects. A non-destructive method using aerial photographs and topographic measurements integrated in a Geographic Information System (GIS) was evaluated to determine the effects of organic and inorganic soil amendments on the growth of millet [Pennisetum glaucum (L.) R. Br.] and Guiera senegalensis J.F. Grmel. Based on aerial photographs, quantitative methods were developed to estimate the dry matter of millet plants and Guiera coppices present in the field each year prior to millet sowing. Integrating digital images of both plant species, measurements of the field's topography and a map of the experimental layout in a GIS allowed successful monitoring of the growth of both species as influenced by phosphorus application and the shrub-crop interaction. Regressions between the dry matter of Guiera coppices and the canopy area were good (r = 0.76 to 0.93) and permitted the calculation of the individual coppice dry matter for the entire field with fewer than 40 destructive measurements. The information on coppices' positions extracted from the aerial photographs and the topographic grid used as covariates explained a significant proportion of the millet growth variability. The use of these covariates also improved the precision of the analysis of variance of millet dry matter data by reducing the residual sum of squares by as much as 33% in the first experimental year. The study demonstrates the potential of non-destructive measurements integrated in a GIS to improve the collection and interpretation of data from field experiment

Multi-site time-trend analysis of soil fertility management effects on crop production in sub-Saharan West Africa

Soil fertility constraints to crop production have been recognized widely as a major obstacle to food security and agro-ecosystem sustainability in sub-Saharan West Africa. As such, they have led to a multitude of research projects and policy debates on how best they should be overcome. Conclusions, based on long-term multi-site experiments, are lacking with respect to a regional assessment of phosphorus and nitrogen fertilizer effects, surface mulched crop residues, and legume rotations on total dry matter of cereals in this region. A mixed model time-trend analysis was used to investigate the effects of four nitrogen (0, 50, 90 or 150 kg/ha) and phosphorus (no fertilizer, 13 kg/ha single superphosphate, 39 kg/ha Tahouca rock phosphate, an additional annual placement of rock phosphate at 4 kg/ha, and as NPK) rates, annually applied crop residue dry matter at 500 and 2000 kg ha-1, and cereal-legume rotation versus continuous cereal cropping on the total dry matter of cereals and legumes. The multi-factorial experiment was conducted over four years (1995-98) at eight locations (Banizoumbou, Sadore, Kara Bedji, Goberi, Gaya, Fada-Kouare, Koukombo and Kaboli), with annual rainfall ranging from 510 to 1300 mm, in Niger, Burkina Faso, and Togo. With the exception of phosphorus, treatment effects on legume growth were marginal. At most locations, except for typical Sudanian sites with very low base saturation and high rainfall, phosphorus effects on cereal total dry matter were much lower with rock phosphate than with soluble phosphorus, unless the rock phosphate was combined with an annual seed-placement of 4 kg ha-1 phosphorus. Across all other treatments, nitrogen effects were negligible at 500 mm annual rainfall but at 900 mm, the highest nitrogen rate led to total dry matter increases of up to 77% and, at 1300 mm, to 183%. Mulch-induced increases in cereal total dry matter were larger with lower base saturation, reaching 45% on typical acid sandy Sahelian soils. Legume rotation effects tended to increase over time but were strongly species-dependen

Changes in bulk and surface properties of two biochar types during 12 months of field ageing in two West-African soils

The study investigated the changes in properties of rice husk and corn cob biochars applied in urban agricultural field soils in Tamale (northern Ghana) and Ouagadougou (Burkina Faso), respectively. The biochars were both pyrolyzed at 500 °C with a batch reactor. Fine polyethylene mesh (litter bags) filled with 10 g of each type of biochar were buried at 20 cm depth in urban fields trials with a 3 x 2 factorial layout replicated 4 times. Factor 1 involved soil management practices at 3 levels: (1) farmers’ practice (FP), (2) 20 t biochar ha-1 and (3) control (no biochar). The second factor was time (duration) at two levels (6 and 12 months). Aged and fresh biochars were analyzed for volatile matter (VM), ash and fixed carbon (FC) contents, pH, effective cation exchange capacity (ECEC), and total surface acidity (Sa) and basicity (Sb). Dissolved organic carbon contents were determined sequentially by cold (cDOC) and hot water extractions (hDOC), respectively and aromaticities of cold water DOC (cSUVA) and hot water DOC (hSUVA) were determined. There was no significant interaction effect of soil management practices and time on measured ageing biochar properties. Time significantly affected most biochar ageing properties except Sa and Sb in rice husk biochar and ECEC in corn cob biochars at 6 months of exposure. In both biochars, Ash content, Fixed carbon (FC), cDOC, hDOC, cSUVA and hSUVA increased whilst pH and volatile matter contents decreased significantly. The hDOC was 2-3 times higher than cDOC contents for both biochars. Aromaticity of DOC contents of aged rice husk biochar exposed to soil management practices and time in the experimental site in Tamale showed persistence with time compared to corn cob biochar exposed in Ouagadougou experimental site. The results imply that rainfall, soil organic matter contents with interplay of soil minerals are key drivers to ageing and sequestration of these biochars and that these forces act at different scales but driven by time

Post Stratification Clarifies Treatment Effects on Pearl Millet Growth in the Sahel

Spatial variation in the growth of pearl millet [Pennisetum glaucum (L.) R. Br.] over short distances is a problem in field experiments in the Sahel, but the causes are still poorly understood. Data from a 3-yr experiment with millet were used to compare four data types for their usefulness for reducing variation not related to treatment: (i) soil chemical data, (ii) residuals of the first year's yield data, (iii) a traditional fertility classification system, and (iv) plant vigor scores. The completely randomized experiment consisted of four factors combined to 48 treatments, replicated twice. There were three levels of millet crop residues (CR), two levels of broadcast P, and four genotypes; the fourth factor had two levels and varied over years. Whereas chemical analyses of the topsoil did not explain overall variation, residuals of plant scores used as covariates led to a reduction in residual variation of 32% for straw and 51% for grain yield in 1991. Most satisfactory, however, was the use of residuals of plant scores to classify plots into two strata of relatively low and high inherent soil productivity (a retrospective procedure called post stratification). In low-productivity plots, a CR application of 2000 kg ha−1 (compared with 500 kg ha−1) increased millet straw yield by an average of 42% and grain yield by 48% for the first 2 yr. In contrast, under high productivity, yields were barely influenced by treatments. The application of P, however, was equally effective in both productivity strata

Tolerant pearl millet (Pennisetum glaucum (L.) R. Br.) varieties to low soil P have higher transpiration efficiency and lower flowering delay than sensitive ones

Abstract Background and aim In the West African Sahel low soil phosphorus (P) and unpredictable rainfall are major interacting constraints to growth and grain yield of pearl millet. Investigating the relationship between transpiration and final yield under the combined effect of water and P stress is fundamental to understand the underlying mechanisms of tolerance and improve breeding programs. Methods We conducted two lysimeter trials using 1 m long PVC tubes (35 cm diameter) filled with a P poor Sahelian soil mimicking soil profiles to assess grain and stover yield, and water use of 15 pearl millet genotypes grown under different P (no P supply or addition of 1.5 g P tube−1) and water (well watered or terminal water stress) regimes. In experiment 2 transpiration was measured twice a week from tube weight differences, and transpiration efficiency (TE) was calculated as dry matter (DM) produced per kg of water transpired. Results Low soil P delayed flowering, and more so in sensitive genotypes. Later flowering of genotypes sensitive to low P made them more sensitive to terminal water stress. Under P limiting soil, genotypes tolerant and sensitive to low P used similar amounts of water (19.8 and 21.7 kg water plant−1, respectively). However, tolerant lines transpired less water prior to anthesis (8.8 kg water plant−1) leaving more water available for grain filling (11 kg water plant−1) while sensitive lines used 14.4 kg water plant−1 pre-anthesis, leaving only 7.2 kg water plant−1 for grain filling. Low soil P decreased grain yield by affecting seed size at harvest and its damage during seed filling overrode the effect of seed size at sowing. Grain yield was positively correlated with water extracted after anthesis. TE was enhanced by P supply, especially in sensitive lines, and TE was higher in tolerant than in sensitive genotypes under low soil P. Conclusions Pearl millet plants tolerant to low P were more resistant to the delay of flowering caused by low P soil and they presented higher transpiration efficiency. The pattern of transpiration was important to cope with terminal water stress under different levels of P availability. Higher transpiration after anthesis, resulting from conservative water mechanism pre-anthesis (higher TE) and possibly by a shorter delay in flowering under low soil P, enhanced grain yield

Cereal/legume rotation effects on cereal growth in Sudano-Sahelian West Africa: soil mineral nitrogen, mycorrhizae and nematodes

Yield increases of cereals following legumes in rotation have been previously reported for West Africa, but little progress has been made to explain the mechanisms involved. At four sites in Niger and Burkina Faso, field trials with pearl millet (Pennisetum glaucum (L.) R. Br.), cowpea (Vigna unguiculata (L.) Walp), sorghum (Sorghum bicolor (L.) Moench) and groundnut (Arachis hypogaea L.) were conducted from 1996 to 1998 to investigate the role of soil mineral nitrogen (Nmin), native arbuscular mycorrhizae (AM) and nematodes in cereal/legume rotations. Grain and total dry matter yields of cereals at harvest were increased by legume/cereal rotations at all sites. Soil Nmin levels in the topsoil were consistently higher in cereal plots previously sown with legumes (rotation cereals) compared with plots under continuous cereal cultivation. However, these rotation effects on Nmin were much larger with groundnut than with cowpea. Roots of rotation cereals also had higher early AM infection rates compared to continuous cereals. The dominant plant-parasitic nematodes found in all experiment fields were Helicotylenchus sp., Rotylenchus sp. and Pratylenchus sp. In sorghum/groundnut cropping systems, nematode densities were consistently lower in rotation sorghum compared to continuous sorghum. Continuous groundnut had the lowest nematode densities indicating that groundnut was a poor host for the three nematode groups. In millet/cowpea cropping systems with inherently high nematode densities, crop rotations barely affected nematode densities indicating that both crops were good hosts. These results suggest that on the nutrient poor Sudano-Sahelian soils of our study, total dry matter increases of rotation cereals compared with continuous cereals can be explained by higher Nmin and AM infection levels early in the season. The site-specific magnitude of these effects may be related to the efficiency of the legume species to suppress nematode populations and increase plant available N through N2-fixation