Effects of supplying silicon nutrient on utilization rate of nitrogen and phosphorus nutrients by rice and its soil ecological mechanism in a hybrid rice double-cropping system

Abstract

This study was conducted to reveal the effects of silicon (Si) application on nutrient utilization efficiency by rice and on soil nutrient availability and soil microorganisms in a hybrid rice double-cropping planting system. A series of field experiments were conducted during 2017 and 2018. The results showed that Si nutrient supply improved grain yield and the utilization rates of nitrogen (N) and phosphorus (P) to an appropriate level for both early and late plantings, reaching a maximum at 23.4 kg/ha Si. The same trends were found for the ratios of available N (AN) to total N (TN) and available P (AP) to total P (TP), the soil microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), microbial biomass phosphorus (MBP), and the ratios of MBN to TN and MBP to TP, at different levels of Si. Statistical analysis further revealed that Si application enhanced rice growth and increased the utilization rate of fertilizer due to an ecological mechanism, i.e., Si supply significantly increased the total amount of soil microorganisms in paddy soil compared to the control. This promoted the mineralization of soil nutrients and improved the availability and reserves of easily mineralized organic nutrients.

Impacts of Fallow Conditions, Compost and Silicate Fertilizer on Soil Nematode Community in Salt–Affected Paddy Rice Fields in Acid Sulfate and Alluvial Soils in the Mekong Delta, Vietnam

“…This result can be explained by the result that the reduced intensive rice cultivation in triple rice cropping system enhanced microbial activity and other soil physicochemical properties [22,62], therefore, it may produce higher food resources for nematode in different trophic structures in soil habitat. Besides, as our explanation in the previous part that silicate fertilizer can stimulate much higher food resource above-and belowground [70,80,82,83], it may provide foods for nematodes with higher trophic functional guilds as omnivores and predator due to prey-predator interaction in the soil food web [54]. Particularly, an increase in bacterivorous footprint was only observed in ASS when compost was added into the proposed system compared to the conventional cropping system.…”

“…Particularly, the application of silicate fertilizer into reduced intensive rice cropping system stimulated the abundance of bacterivorous, omnivorous and predator nematodes in ASS. This result can be explained that the application of silicate fertilizer might increase total amount of microorganisms because it increased available nitrogen (N) and phosphorus (P) [70]. Microorganisms are an essential food for nematode communities, particularly bacterivorous and other omnivorous-predator nematodes [80] Besides, in previous session, we have explained the stimulation of Mesodorylaimus and Rhabdolaimus by silicate fertilization.…”

“…In a previous study, a rotation system of rice and upland crops in a paddy field increased diversity indices [22]. The application of silicate fertilizer strongly increased the microbial food resources for nematodes in soils [70,80]. Moreover, the application of silicate fertilizer in rice cultivation increased abundance of bacteria of betaproteobacteria and cyanobacteria and fungi of ascomycota, basidiomycota, and increased abundance of functional genes involved in labile C degradation, C and N fixation, phosphorus utilization [82].…”

“…Silicate fertilizer may change natural food resources, resulting in the increase of FLN. Several studies have reported that silicate fertilization provides an essential nutrient for growth of Gramineae plants, suppresses pathogens and stimulates the growth of algae and diatoms [67,69,70]; silicate is an essential element for diatoms because they utilize silicic acid to construct their cell walls [71,72]. In paddy fields, algae and diatoms generally exist in the water and they are present on the soil surface during flooding [73,74] and have greater biomass and a positive correlation with salinity water, particularly in the estuarine environment with a range of water salinity from 4.9-8.6 g L −1 [75,76].…”

Significant Synergy Effects of Biochar Combined with Topdressing Silicon on Cd Reduction and Yield Increase of Rice in Cd-Contaminated Paddy Soil

“…Rice is a typical silicon-accumulating crop. Exogenous application of Si could improve the ability of rice to absorb nitrogen (N), phosphorus (P), potassium (K) and other nutrients [17], enhance the photosynthetic capacity and the accumulation of dry matter and ultimately promote rice yield [18,19]. The application of Si also significantly improves the transfer efficiency and distribution rate of N, P and K in rice, which in turn increases rice yield [20].…”