The Effect of Organic Biostimulants on Beneficial Soil Microorganism Activity

Organic biostimulants and organic fertilizers can improve soil health for various horticultural crops. The objectives of these experiments were to determine if biostimulants beneficially increase soil microorganism activity in soilless medium, and additionally measure the impact of synthetic and organic fertilizers with blackstrap molasses on plant nutrient uptake nutrient runoff. It was hypothesized that the addition of biostimulants will increase soil microbe activity. Evolution of soil carbon dioxide was measured by comparing different rates (0, 15, 30, and 45 mL/3.8 L of water) of blackstrap molasses using a randomized block design with 3 replications in nursery containers. Also, a second study using St. Augustinegrass and tomatoes fertilized with organic and synthetic fertilizers was evaluated with and without a biostimulant rate (30 mL/3.8 L of water). The plants were arranged in randomized complete block design with 6 replications. Soil biostimulants did significantly increase the microorganism activity at the 0.05 level. The highest rate of blackstrap molasses improved soil biological activity over a 4-week period. Additionally, fertilizer combined with molasses did show significant increases in soil microbiology for over 5 weeks for both tomatoes and St. Augustinegrass. Molasses increased soil microbial activity but not plant nutrition. Organic fertilizer though resulted in higher levels of phosphorus, calcium, magnesium, and sulfur in plant tissue. Further research is being conducted to measure the influence of biostimulants on the breakdown of composting plant matter. Organic fertilizer slightly increased soil water pH but reduced nutrient load pollution based on a 7-day nutrient effluent study. Total nutrients (nitrates, P, Ca, Mg, and S) runoff was significantly less than synthetic fertilizer. Organic fertilizer reduced nutrient dumping in waste effluent. Organic fertilizers can improve nutrient use efficiency.

HOTSPOTS OF NUTRIENT LOSSES TO AIR AND WATER:AN INTEGRATED MODELING APPROACH FOR EUROPEAN RIVER BASINS

Nutrient pollution of air and water is a persistent problem in Europe.However,the pollution sources are often analyzed separately,preventingthe formulation of integrative solutions.This study aimed to quantify the contribution of agriculture to air,river and coastal water pollution by nutrients.A new MARINA-Nutrients model was developed for Europe to calculate inputs of nitrogen(N)and phosphorus(P)to land and rivers,N emissions to air,and nutrient export to seas by river basins.Under current practice,inputs of N and P to land were 34.4 and 1.8 Tg.yr^(-1),respectively.However,only 12%of N and 3%of P reached the rivers.Agriculture was responsible for 55%of N and sewage for 67%of P in rivers.Reactive N emissions to air from agriculture were calculated at 4.0 Tg.yr^(-1).Almost twofifths of N emissions to air were from animal housing and storage.Nearly a third of the basin area was considered as pollution hotspots and generated over half of N emissions to air and nutrient pollution in rivers.Over 25%of river export of N ended up in the Atlantic Ocean and of P in the Mediterranean Sea.These results could support environmental policies to reduce both air and water pollution simultaneously,and avoid pollution swapping.

Understanding nutrient build-up on urban road surfaces

This article discusses the outcomes of a research project on nutrients build-up on urban road surfaces. Nutrient build-up was investigated on road sites belonging to residential, industrial and commercial land use. Collected build-up samples were separated into five particle size ranges and were tested for total nitrogen （TN）, total phosphorus （TP） and sub species of nutrients, namely, NO2^-, NO3^-, TKN and PO4^3-. Multivariate analytical techniques were used to analyse the data and to develop detailed understanding on build- up. Data analysis revealed that the solids loads on urban road surfaces are highly influenced by factors such as land use, antecedent dry period and traffic volume. However, the nutrient build-up process was found to be independent of the type of land use. It was solely dependent on the particle size of solids build-up. Most of the nutrients were associated with the particle size range 〈150 μm. Therefore, the removal of particles below 150 μm from road surfaces is of importance for the removal of nitrogen and phosphorus from road surface solids build-up. It is also important to consider the difference in the composition of nitrogen and phosphorus build-up in the context of designing effective stormwater quality mitigation strategies.

Scientifically advanced woody media for improved water quality from livestock woodchip heavy-use areas

Overwintering cattle on pastures in many areas can damage the pasture and lead to impaired water quality. During these times, use ofa woodchip heavy-use area （HUA） presents advantages such as a soft, supportive, and dry toot surface for animals and protection of the pasture and pasture soils. However, woodchip HUAs can also be a centralized source of high nutrient loads due to their drainage outflows. A column study was conducted to assess the nutrient load reduction potential of： 1 ） six types of wood media （including torrefied wood media and biochar） that could be used in a woodchip HUA versus a gravel control, and 2） providing a 48 h retention time within the wood media to enhance nitrogen removal through denitrification. The woody media provided significant liquid waste volume reduction compared to the gravel in simulated events （53%-61% vs. 39% reductions, respectively）, and there may be additional liquid storage capacity in the woodchips not utilized during these rapid events. Substantial total nitrogen removal by the wood treatments （mean removal efficiencies 〉 50%） was observed across the sinmlated events, although nitrate leaching also occurred. Nitrate removal was enhanced during the 48 h retention test which showed removal was governed by availability of labile carbon （i.e., fresh woodchips exhibited 〉 70% nitrate removal）. The retention test also indicated biochar mixtures provided some of the best total phosphorus removal, but the greatest benefits across all parameters was provided by the Mixed Hardwood treatment.