Three decades of shade trees improve soil organic carbon pools but not methane uptake in coffee systems.

The rapid expansion of coffee plantations in tropical area at the cost of natural forest may suppress the methane (CH4) uptake and change the soil fertility. However, observations on soil CH4 uptake rates and the ecological consequence studies on coffee-based plantations are sparse. The objectives of this study were to characterize the dynamics of CH4 uptake among natural forest, coffee monoculture (CM), and coffee intercropping with shade tree (CI), and to evaluate the key drivers of soil CH4 uptake. Results showed that the conversion of forest into 25-year and 34-year CM plantations significantly reduced the soil organic carbon (SOC) content by 57% and 76%, respectively, whereas CI plantation profoundly increased the SOC by 20%-76% compared with CM plantation. Although soils of forest, CM and CI functioned exclusively as CH4 sinks, the CM and CI plantations significantly decreased the ambient CH4 uptake rates by 64%-83% due to soil moisture shift and soil nitrate availability by using chemical fertilizer. Interestingly, the potential CH4 uptake of CM and CI plantations did not decrease and in some treatments, was even higher than that of the natural forest. Potential CH4 uptake showed a negative correlation with soil pH and SOC content, but a positive correlation with soil available phosphorus (AP). Collectively, although the SOC and soil pH were increased through intercropping with shade trees for decades, the inhibition of atmospheric CH4 uptake was still difficult to alleviate.

Different ratios of Canna indica and maize-vermicompost as biofertilizers to improve soil fertility and plant growth: A case study from southwest China.

Vermicomposting is recommended as an eco-friendly technology for an organic amendment to avoid the excessive use of inorganic fertilizers, which are causing environmental pollution. Here, this study evaluated soil fertility and plant growth after vermicompost amendment using reclaimed wetland plants and manure. A pot experiment was conducted to assess the seven treatments for nutrient recovery and plant growth: a control group without any fertilization (CK); four groups with vermicompost prepared from different ratios of ecological wetland plant residues, maize, and pig manure (V1, 4:6; V2, 5:5; V3, 6:6; and V4, 7:3); one group with only Canna indica (V5, Ci), and a group with synthetic fertilizers (NPK). The results showed the remarkable impacts of Ci-vermicompost and different ratios of organic fertilizer on soil fertility and plant height (28.8%) as major outcomes. In addition, vermicompost substantially increased soil total nitrogen (60.5%), soil organic matter (60.9%) including dissolved organic carbon (52.2%), and shoot biomass (V4, three-fold increase) compared with NPK and CK. Overall, the findings of this study suggest that vermicomposting combined with wetland plants is a feasible method for organic amendments and offers an innovative approach for recycling ecological waste to produce nutrient-rich organic fertilizers, reduce environmental damage, and improve crop production.

[Yield formation of different single-season rice (Oryza sativa L. ) types and its relationships with meteorological factors in Yunnan Province of Southwest China].

By using the 1994-2010 observation data of paddy rice growth period and yield from 14 agro-meteorological stations at different altitudes in Yunnan Province, this paper studied the rice yield formation and the effects of meteorological factors on low-yield rice yield components. According to the systematic cluster analysis of rice yield components and the rice types at the 14 stations, the rice was divided into 4 types, i. e., low-yield japonica rice, low-yield indica rice, high-yield japonica rice, and high-yield indica rice. The analysis of the yield components of the 4 rice types showed that there was a significant positive correlation between the spikelet number per square meter (sqm) and the rice yield. The yield of low-yield japonica was mainly affected by the seed setting rate and the spikelet number per sqm. For the other three rice types, the spikelet number per sqm had greater effects on the rice yield. The low-yield japonica rice was mainly affected by low temperature. At booting stage, low temperature decreased the spikelet number and the productive panicle number of unit sqm. At booting and flowering stages, low temperature increased the empty grain rate, and the effects of average temperature, average maximum temperature, and cold accumulated temperature were greater. At pre-milk stage, low temperature increased the unfilled grain rate, and meanwhile, decreased the 1000-grain mass. The yield components of low-yield indica rice were obviously affected by multiple meteorological factors. A certain degree of warming at tillering and jointing stages was not beneficial to the increase of productive panicle number per sqm of low-yield indica rice, but the more sunshine hours and the greater average diurnal temperature range at tillering stage was beneficial to the increase of the productive panicle number per sqm. There was a parabolic relationship between the temperature and sunshine hours at tillering and jointing stages and the spikelet number per panicle. The low temperature at flowering stage affected the empty grain rate of low-yield indica rice to a certain extent, while the high temperature and less rain at pre-milk stage not only increased the unfilled grain rate, but also distinctly reduced the 1000-grain mass.