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Questions related from Nguyen Hue
Most biochars have alkaline pH (above 8). That could be explained by Ca, Mg, K oxides released during the charring process (pyrolysis). Yet, some biochars have acidic pH (less than 6). What may be...
06 June 2018 2,399 5 View
Soil acidity is often characterized by high Al/Mn and low Ca/Mg. Dolomite or calcite (i.e., agricultural lime) can be used to mix with the surface soil and correct its acidity. But for tree crops,...
05 May 2018 2,188 0 View
It has been reported that biochars can retain anions, such as nitrate and phosphate. Specific adsorption could explain P retention, but positive charge must be present to electrostatically retain...
02 February 2018 6,224 1 View
It is understood that PCA can be used to combine/reduce rather large numbers of related variables into a few independent (orthogonal) factors for statistical analysis and interpretation. Yet, are...
08 August 2017 2,523 1 View
I need to sterilize about 100 kg soil for a greenhouse experiment. Knowing that methyl bromide has been banned and sodium azide or toluene is not appropriate (because I want to study N and C), is...
05 May 2016 411 2 View
We know that biochars have several properties from tiny pores that can retain water and protect microorganisms to surface functional groups (e.g., COOH, OH, C=O, etc) that can retain plant...
05 May 2016 4,880 4 View
Since different biochars have different properties, what kind of biochars should be used as a soil amendment for nutrient-poor, acidic tropical soils? The goal is to improve soil productivity and...
05 May 2016 740 4 View
Decades ago ferrihydrite and allophane were considered amorphous with no X-ray patterns. But now with modern techniques, Can we characterize these minerals (substances) well?
12 December 2015 3,123 0 View
Biochars are thought of as 'inert' carbon materials, yet their reported CEC are relative high (over 20 centimole of charge per kg). Are these values correct? or the methods of measurement are not...
10 October 2015 2,169 6 View
Eutrophication is a serious problem in many water ways from China to the US gulf coast. It is believed to be caused by high P and N from erosion and run-off. Are there any good ways to control it?
05 May 2015 5,965 2 View
h-index is sometimes listed as a measure of research/citation (quality). How meaningful is it? and what is the expected h-index of a newly-hired assistant professor?
03 March 2015 4,561 7 View
One of cultural practices in organic farming is to spray vegetable crops with compost tea. It is believed that compost tea would provide plant nutrients, stimulate growth (via growth hormones in...
02 February 2015 1,388 9 View
Green sand (K feldspar?) is considered a natural source of potassium (K) and is acceptable to organic farming. However, its K ( about 5 - 6%) is released very slowly. Are there any...
01 January 2015 3,792 3 View
Aluminum (Al) toxicity is a serious constraint to crop production in many regions around the world. The first step in correcting this problem is to identify it. Should we use exchangeable...
11 November 2014 9,605 19 View
It is a common belief that vermi-compost (compost made with earthworms) is better than thermo-compost (microbial decomposition with temperatures as high as 60 0C) in quality and soil amendment...
10 October 2014 5,769 10 View
Soil quality can be many things to different people. However,should certain metrics (e.g., soil CEC, microbial population and diversity/activity, soil aeration, bulk density) be included as core...
10 October 2014 7,122 9 View
As most agronomists and soil scientists know, Al and As are considered toxic to nearly all crops. Yet, at very low concentrations (part per billion in soil solution) could these two elements...
09 September 2014 5,971 3 View
In organic/sustainable farming, compost is a good (major?) source of N and micro-nutrients for crops. How to predict/synchronize N release from compost and N need by a crop is important to a...
09 September 2014 1,999 4 View
Water soluble nitrate sometimes can be measured quickly as absorbance at 206 and/or 250 nm wavelengths. However, other organic molecules, especially those with double bonds also absorb radiation...
09 September 2014 6,101 7 View
Organic matter can be estimated quickly and rather easily by burning a soil sample at 300 oC in a furnace for 4-6 hours. How well correlated is such a value with soil organic carbon as measured by...
09 September 2014 9,124 6 View
Recently several ion-selective electrodes, such as those for NH4, NO3, Cl, F. K, Ca, etc, are becoming available. If I understand it correctly, these electrodes measure ion activity, meaning ionic...
09 September 2014 6,515 2 View
As we know, As and P can compete with each other for soil adsorption as well as for plant uptake. How can we predict As phyto-availability upon fertilization with a P source?
09 September 2014 4,076 3 View
A SPAD (soil plant analysis development) meter is sometimes used to indicate relative chlorophyll content in leaves of several crops. Such as device measures greenness of an object. What...
09 September 2014 5,806 7 View
Biochars are thought to be a very stable form of carbon, yet normal CEC measurement (e.g., Neutral 1 M ammonium acetate) would yield very high CEC values (ranging from 15 - 40 cmolc/kg). Where are...
08 August 2014 1,239 14 View
