Tag: fertilizer
Climatic variability and the role of trees in influencing maize productivity in semi-arid Kenya
Effects of soil management on aggregation and organic matter dynamics in sub-Saharan Africa
Maintenance of soil organic matter (SOM) is important for soil quality and agricultural productivity. However, little is known about the effects of management practices of different intensities on soil aggregation and SOM dynamics in tropical arable cropping systems of sub-Saharan Africa. We investigated the influence of land use practices and management intensity on soil aggregation and SOM dynamics across 12 long-term field experiments in eastern and western Africa. Aggregate size distribution and SOM were measured in arable systems under contrasting management intensities of high carbon, low carbon and a fallow. Aggregate stability indices and SOM were generally higher in the fallow compared to the arable systems. Fallowing and high carbon inputs in arable soils, significantly improved aggregate stability and carbon (C) and nitrogen (N) stabilization in whole soil, and in aggregate fractions. In contrast, no significant improvements in soil aggregation and C and N stabilization were found when organic inputs were either applied in low quantities or not applied at all, thus resulting in low carbon in soils. Our study showed that fallowing and long-term application of organic amendments alone or in combination with mineral fertilizers were the best among the practices tested in this study, for enhanced C and N stabilization in soils with the subsequent benefits of improving soil physical and chemical properties. These results emphasize the importance of management for sustaining soil quality. It is recommended that fallowing be an integral part of sustainable soil management strategies in these regions.
Data in brief on inter-row rainwater harvest and fertilizer application on yield of maize and pigeon-pea cropping systems in sub humid tropics
Data in this article presents rainfall variability in the season and between seasons, yield of maize (Zea mays cv. TMV1) and pigeon-pea (Cajanus cajan cv. Babati White) under sole crop and intercropping. Yield of maize and pigeon-pea is analyzed under inter-row rainwater harvesting practices and fertilizer application in the field. Sole cropping and intercropping biological and/or economic yield are used to determine land use efficiency through land equivalent ratio. Comparisons between sites and seasons are done using a T-test.
Growth and yield responses of cotton (Gossypium hirsutum) to inorganic and organic fertilizers in southern Malawi
Fertilizer trees, the nitrogen-fixing legumes, such as gliricidia (Gliricidia sepium) and tephrosia (Tephrosia spp.) have been used to improve soil fertility for higher crop yields in nitrogen deficient soils. Many studies have focused on how these fertilizer trees improve maize yield, but there has been a dearth of information on the effect of fertilizer tree species on cotton growth and yield. A study was undertaken for two cropping seasons (2012/13 and 2013/14) with the objective of assessing IRM 81 cotton growth and yield responses to tephrosia and/or gliricidia biomass with or without inorganic fertilizer application. Boll opening significantly varied (P < 0.0001) with treatments and early boll opening was observed in plots where only inorganic fertilizer was applied. Higher lint yield (mean of 1397 kg/ha) was obtained in the second cropping season than in the first cropping season (480 kg/ha) and the application of gliricidia biomass with fertilizer gave the highest lint yield (2121 kg/ha). The lowest lint and seed yields were obtained from plots where tephrosia biomass only was applied. It is concluded that the use of gliricidia biomass with inorganic fertilizer improved cotton yields. The high amount of gliricidia biomass (due to prolific coppicing) applied contributed to higher cotton lint yields with reduced rates of inorganic fertilizer application, making gliricidia-cotton intercropping a cost-effective option to smallholder farmers. © 2016 Springer Science+Business Media Dordrecht
Improved accuracy and reduced uncertainty in greenhouse gas inventories by refining the IPCC emission factor for direct N2O emissions from nitrogen inputs to managed soils
Most national GHG inventories estimating direct N2O emissions from managed soils rely on a default Tier 1 emission factor (EF1) amounting to 1% of nitrogen inputs. Recent research has, however, demonstrated the potential for refining the EF1 considering variables that are readily available at national scales. Building on existing reviews, we produced a large dataset (n = 848) enriched in dry and low latitude tropical climate observations as compared to former global efforts and disaggregated the EF1 according to most meaningful controlling factors. Using spatially explicit N fertilizer and manure inputs, we also investigated the implications of using the EF1 developed as part of this research and adopted by the 2019 IPCC refinement report. Our results demonstrated that climate is a major driver of emission, with an EF1 three times higher in wet climates (0.014, 95% CI 0.011–0.017) than in dry climates (0.005, 95% CI 0.000–0.011). Likewise, the form of the fertilizer markedly modulated the EF1 in wet climates, where the EF1 for synthetic and mixed forms (0.016, 95% CI 0.013–0.019) was also almost three times larger than the EF1 for organic forms (0.006; 95% CI 0.001–0.011). Other factors such as land cover and soil texture, C content, and pH were also important regulators of the EF1. The uncertainty associated with the disaggregated EF1 was considerably reduced as compared to the range in the 2006 IPCC guidelines. Compared to estimates from the 2006 IPCC EF1, emissions based on the 2019 IPCC EF1 range from 15% to 46% lower in countries dominated by dry climates to 7%–37% higher in countries with wet climates and high synthetic N fertilizer consumption. The adoption of the 2019 IPCC EF1 will allow parties to improve the accuracy of emissions’ inventories and to better target areas for implementing mitigation strategies.
Effect of fertilizer inputs on productivity and herbage quality of native pasture in degraded tropical grasslands
The practice of applying fertilizer inputs on an unimproved natural pasture is limited in tropical grasslands. A study was conducted to evaluate the response of degraded natural pasturelands in terms of species composition, forage yield, and quality to the application of different types of fertilizer. The study was conducted in two districts in the central Rift Valley of Ethiopia with contrasting agroecologies. The treatments were control (no application of fertilizer), commercial fertilizer (50 kg urea ha–1 and 100 kg diammonium phosphate [DAP] ha–1), cattle manure (7.5 t ha–1), wood ash (3 t ha–1), and lime (7.5 t ha–1). Soil physical properties were not altered following application of the treatments, but chemical properties, including soil pH (P < .01), electroconductivity (EC) (P < .001), total nitrogen (TN), and P (P < .001) were affected. Soil TN increased from 0.11 to 0.32% following the application of cattle manure. The pH increased from 5.9 to 7.3 with wood ash application. Herbage dry matter (DM) yield increased (P < .001) from 1.88 to 6.65 t ha–1 with chemical fertilizer. The herbage crude protein content increased (P < .01) from 96 to 157 g kg–1 with manure application. On the other hand, the neutral detergent fiber tended to decrease (P < .05) following manure application. Partial cost-benefit analysis indicated a positive economic gain from the direct sale of pasture hay for all treatments except for lime. The results indicated that fertilizer inputs offer feasible options to improve pasture productivity and enable rural farmers to benefit from their land resources.
Mismatch between soil nutrient requirements and fertilizer applications: Implications for yield responses in Ethiopia
Lack of accurate information about soil nutrient requirements coupled with limited access to appropriate fertilizers could lead to mismatch between soil nutrient requirements and fertilizer applications. Such anomalies and mismatches are likely to have important implications for agricultural productivity. In this paper we use experimental (spectral soil analysis) data from Ethiopia to examine farmers’ response to soil nutrient deficiencies and its implications for yield responses. We find that farmers’ response to macronutrient (nitrogen and phosphorus) deficiencies is not always consistent with agronomic recommendations. For instance, we find that farmers in our sample are applying nitrogen fertilizers to soils lacking phosphorus, potentially due to lack of information on soil nutrient deficiencies or lack of access to appropriate fertilizers in rural markets. On the other hand, farmers respond to perceivably poor-quality soils and acidic soils by applying higher amount of nitrogen and phosphorus fertilizers per unit of land. We further show that such mismatches between fertilizer applications and soil macronutrient requirements are potentially yield-reducing. Those farmers matching their soil nutrient requirements and fertilizer application are likely to enjoy additional yield gains and the vice versa. Marginal yield responses associated with nitrogen (phosphorus) application increases with soil nitrogen (phosphorus) deficiency. Similarly, we find that farmers’ response to acidic soils is not yield-enhancing. These findings suggest that such mismatches may explain heterogeneities in marginal returns to chemical fertilizers and the observed low adoption rates of chemical fertilizers in sub-Saharan Africa. As such, these findings have important implications for improving input management practices and fertilizer diffusion strategies.
Comparison of resilience of different plant teams to drought and temperature extremes in Denmark in sole and intercropping systems
Intercropping (IC) can reduce nitrogen fertilizer requirements, supress weeds, and improve crop yields and yield stability. Three field trials were conducted in Denmark in 2018 with intercropping and sole crops (SC) using spring wheat, barley, faba bean and field pea to compare productivity under five fertilizer levels. The trials were carried out using in a split-plot design with four. Anomalous weather during the 2018 cropping season created drought conditions and high temperatures above 31°C. No effect of fertilizer treatment was found, and total dry matter and grain yields were supressed in all systems. Wheat grain yields averaged 2.14 t ha−1 across systems, ranging from 1.58 t ha−1 as a component of the IC to 2.44 t ha−1 as SC, and barley grain yields averaged 2.35 t ha−1. Faba bean yielded 1.78 t ha−1 as SC, but failed in the IC. Pea failed in both systems. Intercropping barley with cover crops had no effect on grain yield or total dry matter. These results suggest that intercropping provided no production advantage during a drought and illuminate the need to continue conducting research and breeding on drought-resistant cultivars.
How does replacing natural forests with rubber and oil palm plantations affect soil respiration and methane fluxes?
Replacement of forest by agricultural systems is a major factor accelerating the emissions of greenhouse gases; however, related field studies in the tropics are very scarce. To evaluate the impact of forest transition to plantations on soil methane (CH4) and respiration (CO2) fluxes, we conducted measurements in an undisturbed forest, a disturbed forest, young and old rubber plantations, and an oil palm plantation on mineral soil in Jambi, Sumatra, Indonesia. Methane fluxes and their controlling variables were monitored monthly over fourteen months; soil respiration was measured less frequently. All of the plantations were managed by smallholders and had never been fertilized. To assess the effect of common management practices in oil palm plantations, we added urea at a rate of 33.3 kg N/ha and thereafter monitored intensively soil CH4 fluxes. The soil acted as a sink for CH4 (kg CH4‐C·ha−1·yr−1) in the undisturbed forest (−1.4 ± 1.0) and young rubber plantation (−1.7 ± 0.7). This was not the case in the other land‐use systems which had fluxes similar to fluxes in the undisturbed forest, with 0.4 ± 0.9, −0.2 ± 0.3, and 0.2 ± 0.7 kg·ha−1·yr−1 in the disturbed forest, old rubber plantation, and oil palm plantation, respectively. In the oil palm plantation, there was no inhibitory effect of nitrogenous fertilizer on methanotrophy. Annual soil respiration (Mg CO2‐C·ha−1·yr−1) was higher in the oil palm plantation (17.1 ± 1.9) than in the undisturbed forest (13.9 ± 1.2) while other land‐use systems respired at a similar level to the undisturbed forest (13.1 ± 1.4, 15.9 ± 1.7, and 14.1 ± 1.0 in the disturbed forest, young, and old rubber plantations, respectively). Substrate (litterfall and soil) availability and quality exerted a strong control over annual fluxes of both gases along the land‐use gradient. Temporal variation in CH4 was extremely high and in respiration fluxes was moderate, but was not specifically linked to seasonal variation. Further comprehensive and long‐term research is critically needed to determine more thoroughly the direction and magnitude of changes in soil trace gas emissions as affected by forest‐to‐plantation conversion in the tropics.