Effect Of Chemical Fertilizer Application Research Articles

Does rice paddy management increase soil organic carbon in the warm temperate and tropical regions?

Enhancing soil organic carbon (SOC) storage in agricultural fields is an effective option for climate change mitigation and food security. In temperate regions, rice farming under paddy is known to increase SOC stock due mainly to the reduced decomposition caused by prolonged submerged conditions compared to the cropping practices under non-flooded conditions. It remains unclear, however, if and to what extent rice paddy management increases SOC storage in warmer climate regions where decomposition is much faster. We thus examined the factors controlling the SOC stock and the net change in SOC normalized to the duration under paddy (ΔSOC) at paddy fields in warm temperate (21 sites) and tropical climatic regions (11 sites) from peer-reviewed literature which was concentrated to Asia. Using collected data (e.g., SOC content, bulk density, mean annual temperature (MAT), precipitation, management duration, soil management, crop rotation), we evaluated predictor variables that account for ΔSOC variability (i.e., mean decrease accuracy) by random forest regression. The mean paddy duration for all data (n = 170) was 22 years. Average SOC stock and ΔSOC at 0–20 cm depth were 38 ± 1.45SE Mg C ha−1 and 0.34 ± 0.04SE Mg C ha−1 yr−1, respectively, indicating that continuous paddy management had a positive effect on SOC storage in both climatic regions. SOC stock was two-fold higher and ΔSOC was four-fold higher in the warm temperate region compared to the tropical region (p < 0.05). The best predictor variables for ΔSOC were MAT followed by soil management and then paddy duration. While organic amendment including both straw and manure increased ΔSOC in both warm temperate and tropical paddies, we did not detect a positive effect of chemical fertilizer application alone or crop rotation type (e.g., rice-upland vs rice-rice). Despite high variability, ΔSOC in the warm temperate region significantly declined over time from 0.82 ± 0.10 Mg C ha−1 yr−1 (< 20 yrs) to 0.22 ± 0.06 Mg C ha−1 yr−1. While SOC stock was 50% lower, the tropical paddies showed no clear decline in ΔSOC up to 41 years (0.04–0.21 Mg C ha−1 yr−1). These results suggest that SOC accretion might have reached equilibrium after 20 years of paddy practice in the warm temperate region and, if so, ΔSOC is likely to diminish to zero in the near future. In tropical paddy fields, on the other hand, slow SOC build-up may continue for a longer term although the ΔSOC value itself is not high. While the current study showed the efficacy of paddy management on SOC build-up under the warmer climate regions, further study on the rate and qualitative changes is necessary to evaluate the trade-offs between soil fertility improvement (e.g., soil N build-up) and methane emission.

Crop residue retention increases greenhouse gas emissions but reduces chemical fertilizer requirement in a vegetable-rice rotation

Retaining crop residues on site after harvesting can maintain soil fertility, reduce fertilizer requirements and restore soil organic carbon on intensively cultivated land. However, how crop residue retention and reduced chemical fertilizer application affect greenhouse gas emissions and crop yield in vegetable-rice rotations is poorly understood. We studied the effect of chemical fertilizer application alone (control, without straw retention), straw retention with 100 % nitrogen fertilizer application (STF) or with three levels of reduced chemical fertilizer application (SFR1, SFR2 and SFR3) in a vegetable-rice rotation in a mesocosm system. In the vegetable season, crop yield was maintained but the agronomic efficiency (AE) was higher in SFR1, SFR2 and SFR3 as compared to STF and the control. In the rice season under flooded condition, the methanogens were higher in SFR1, SFR2 and SFR3 compared to the control, but not different between STF and SFR1. The STF showed higher methane and nitrous oxide emissions, but carbon dioxide emissions and AE remained unaffected compared to the control in the vegetable-rice rotation. The SFR2 and SFR3 treatments maintained crop yields, increased AE, and decreased N2O emissions as compared with STF, but the CH4 emissions were 29.8 % lower in SFR2 than SFR3 in the vegetable-rice rotation. We concluded that straw retention with reduced chemical fertilizer application can maintain crop yield in a vegetable-rice rotation but has the potential to increase CH4 emissions in the rice cultivation season.

The Green Manure (Astragalus sinicus L.) Improved Rice Yield and Quality and Changed Soil Microbial Communities of Rice in the Karst Mountains Area

The use of green manure plants for soil restoration is a viable agricultural practice that can mitigate soil degradation and biodiversity loss caused by the long-term application of inorganic fertilizers. However, the effects of green manure on soil microbial communities, rice yield, and quality in the karst mountains are largely unknown. The effects of no chemical fertilizer, chemical fertilizer, chemical fertilizer + different Astragalus sinicus L. (Chinese milk vetch, CMV) treatments on the microbial community, soil enzyme activities, soil nutrient content, and crop yield were investigated through field experiments. A moderate application of chemical fertilizer with green manure can increase chlorophyll content, increase effective rice spikes, positive impact on rice yield, and increase crude protein, etc. Additional application of the moderate amount of CMV can increase alkali-hydrolyzable nitrogen and available phosphorus (a significant increase of 54.87–72.65%), improve microbial biomass carbon (MBC) and microbial biomass nitrogen (MBN) (CFMV2 significantly increased by 22.16%), improve soil urease and phosphatase activities, and the urease activity increased by 43.43–69.24% with CMV application compared to CK. Moreover, all bacterial communities were dominated by three major phyla (Proteobacteria, Chloroflexi, and Acidobacteria), where the application of chemical fertilizer with CMV increased the ratio of abundance of Proteobacteria and Acidobacteria in rice soils, and the effect of chemical fertilizer application on the dominant bacteria was regulated to some extent by additional green manure application, which may have a beneficial effect on rice yield. Therefore, we conclude that the rational use of chemical fertilizers with CMV (22,500 kg ha−1) in karst landscapes is one of the effective measures to achieve efficient and sustainable use of rice fields.

Propagation and characterization of viable arbuscular mycorrhizal fungal spores within maize plant (Zea mays L.).

The harmful effect of chemical fertilizer application on human health and the environment as a modern method of meeting the food demand of the increasing world population demands an urgent alternative that is environmentally friendly, which will pose no harm to human health and the environment. Arbuscular mycorrhizal fungi (AMF) are beneficial soil microorganisms that provide various ecological functions in increasing soil fertility and enhancing plant growth. This present study aimed to propagate, characterize and examine the effect of viable arbuscular mycorrhizal fungal spores on maize (Zea mays L) hosts using molecular methods. The propagation of AMF in the host plant using sterile soil and vermiculite was conducted in the greenhouse. The effect of AMF inoculation revealed a significant difference (P > 0.05) in maize growth, root colonization and AMF spore count when compared with the control. In all the parameters measured in this study, all the AMF spores propagated had a positive effect on the maize plant over the control, with the highest value mostly recorded in Rhizophagus irregularis AOB1. The molecular characterization of the spore using a specific universal primer for Glomeromycota established the success of the propagation process, which enhanced the classification of the AMF species into Rhizophagus irregularis OAB1, Glomus mosseae OAB2 and Paraglomus occultum OAB3. This finding will be a starting point in producing arbuscular mycorrhizal inoculum as a biofertilizer to enhance plant growth promotion. © 2021 Society of Chemical Industry.

根瘤菌剂现存问题初探

根瘤菌有促进豆科作物生长及产量的作用，能减少施用化肥带来的副作用并降低农业生产的成本。目前，根瘤菌的实际应用受到部分菌剂产品质量因素的限制。本文就商用根瘤菌剂应用中遇到的菌种选育效率低、菌剂污染率高、有效期短等问题予以探讨，为根瘤菌剂的深入研究和应用提供一些参考。 Rhizobium is found excellent in promoting growth and yield of legume crops, which decreases the cost of agricultural production and the side effect of chemical fertilizer application. Currently, Rhizobium inoculants have not been widely used in agriculture. Currently, the practical applications of Rhizobium are restricted by quality factors of some inoculants. In this paper, we discussed briefly the factors such as low strain breeding efficiency of Rhizobium, serious contamination and short shelf life of inoculants, to provide some reference to the further research and application of commercial Rhizobium inoculants.

The effect of chemical fertilizer application on carbon input and export in soil—A pot experiment with wheat using natural 13C abundance method

The enhancement of soil organic carbon (SOC) is important for sustainable agriculture, while changes in SOC depend on the balance between carbon (C) input and export. To investigate how chemical fertilizers contribute to C input (e.g. plant-derived C) and export (e.g. original SOC decomposition) in soil, a wheat (a C3 plant) pot experiment was conducted using a Phaeozem that had previously been used to cultivate maize (a C4 plant). The natural 13C abundance method was used to quantify wheat-derived SOC (WSC) and microbial respiration using the original SOC (Rmicrobial) during the wheat growing season. The wheat grain, WSC, wheat-derived C (WDC: including WSC, root and stubble biomass C) and Rmicrobial-derived CO2 emission (SCE) in fertilized treatments increased by 4.8–31.1%, 48.9–122.4%, 21.3–62.2% and 6.0–51.8%, respectively, when compared to unfertilized treatments. The total SOC in the post-experimental soil increased by 0.14–0.97% when compared to pre-experimental soil because the WSC input was larger than the SCE export, and it would be increased further if wheat root and stubble biomass C were included. Therefore, application of chemical fertilizer not only directly increases crop yield, but also indirectly contributes to C sequestration by favoring crop growth and crop-derived C input in soil.

Effect of Chemical Fertilizer Application on the Growth and Nutrient Contents in Leaflet of Sago Palm at the Rosette Stage

Effect of Chemical Fertilizer Application on the Growth and Nutrient Contents in Leaflet of Sago Palm at the Rosette Stage

Effect of chemical fertilizer application on grain yield in Qitai County, Xinjiang Uygur Autonomous Region

根据新疆奇台县1989～2005年化肥施用量和粮食单产数据, 采用趋势线法分析了该县化肥单位面积施用量的时间序列变化, 并采用相关分析对化肥施用量与粮食单产的关系进行探讨。结果表明: 奇台县化肥单位面积施用量受粮食价格及化肥价格变化的影响较大, 从1989年的65.65 kg·hm^-2上升到最大值1998年的196.6 kg·hm^-2后下降, 整个时间序列曲线呈抛物线状, 且N、P、K施用比例较为合理, 为促进粮食增产发挥了作用。1989～2005年粮食单产与单位面积化肥施用量存在明显的正相关关系, 随施肥量的增加, 粮食单产也趋于增加, 当化肥施用量达到170 kg·hm^-2时, 再增加化肥施用量对粮食的增产效果已不明显。因此, 该县今后在粮食种植过程中应防止过量施肥, 推广科学施肥, 以更大程度地提高粮食产量。