ABSTRACT
Biochar application may mitigate N2O emissions and increase crop yield, yet little is known about microbial dynamics variation. To investigate the potential of increasing yield and reducing emissions of biochar in tropical areas and the dynamic mechanism of related microorganisms, a pot experiment was conducted to investigate the biochar application on pepper yield, N2O emissions, and dynamic variation of related microorganisms. Three treatments were applied:2% biochar amendment (B), conventional fertilization (CON), and no nitrogen (CK). The results showed that the yield of the CON treatment was higher than that of the CK treatment. Compared with that of the CON treatment, biochar amendment significantly increased the yield of pepper by 18.0% (P<0.05), and biochar amendment could increase the content of NH+4-N and NO-3-N in soil in most periods of pepper growth. Compared with that in the CON treatment, the B treatment significantly reduced cumulative N2O emissions by 18.3% (P<0.05). Ammonia oxidizing archaea (AOA)-amoA and ammonia oxidizing bacteria (AOB)-amoA were very significantly negatively correlated with N2O flux (P<0.01). N2O flux was significantly negatively correlated with nosZ gene abundance (P<0.05). This indicated that N2O emission may have mainly resulted from the denitrification process. In the early stage of pepper growth, biochar significantly reduced N2O emissions by reducing the value of (nirK+nirS)/nosZ, whereas in the late stage of pepper growth, the value of (nirK+nirS)/nosZ of the B treatment was higher than that of the CON treatment, resulting in higher N2O flux in the B treatment. Therefore, biochar amendment could not only increase vegetable production in tropical areas but also reduce N2O emissions, which can be used as a new strategy to improve soil fertility in Hainan Province and other tropical areas.
Subject(s)
Ammonia , Vegetables , Archaea , SoilABSTRACT
Intercropping of maize and potato, as an important intercropping planting pattern, has a prominent advantage of resource utilization and yield. However, contribution of nutrient uptake and utilization to crop yield advantage and its response to N application rates remain unclear. Through a 2-year plot experiment, including maize monoculture, potato monoculture and maize intercropping with potato at 4 N-fertilized levels of N0(0 kg·hm-2), N1(125 kg·hm-2), N2(250 kg·hm-2) and N3(375 kg·hm-2), nutritional contribution of yield advantage of intercropping was studied. The results showed that weighted average uptake of nitrogen, phosphorus and potassium was gradually increased with N application rate in monocultures, but increase followed by a decrease in intercropping. Compared with monoculture at the same N level, nutrient uptake advantage of intercropping was the highest at N1, which increased nitrogen, phosphorus and potassium uptake by 14.9%, 38.6% and 27.8%, respectively. However, the nutrient use efficiencies were highest in intercropping at N0 and N3 with increment of 3.5%-14.3% for nitrogen, 3.5%-18.5% for phosphorus and 10.6%-31.6% for potassium. Maize and potato intercropping had a significant yield advantage at N0 and N1. Yield advantage in intercropping attributed to improvement of nutrient use efficiency at N0 while to increase of nutrient uptake at N1. To utilize the yield advantage from nutrient uptake, controlling input of nitrogen fertilizer is necessary in intercropping.
