Connections to Next Generation
We developed two classroom experiments that mirror recent experiments conducted by scientists: effects of biochar on (1) plant growth
and (2) soil respiration. Both experiments align with NGSS through
addressing disciplinary core ideas, crosscutting concepts, and science
practices (Table 2).
The experiments follow the claim, evidence, reasoning (CER)
instructional framework (McNeill & Krajcik, 2008), in which students
construct a scientific argument based on experimental evidence from
the students’ experiments and from published studies. This integrated
approach encourages students to use multiple lines of evidence, including their own observations, to support a claim with reasoning.
Soil & Plant Science Classroom
We describe two classroom experiments that were codeveloped by
K–12 educators and university researchers and conducted in classroom settings. The data shown here were collected by students.
Prior to conducting the experiments, provide students with an
introduction to biochar and its application in soils and agriculture.
Ask students to observe biochar and different soil types under a
microscope and discuss differences in properties such as porosity
(Figure 1) and pH (Appendix 1). Discuss how different properties
of the biochar and soil they observed might influence plant growth
and soil respiration.
Experiment 1: Plant Growth
Biochar is typically added to agricultural soils, and scientists are
interested in how biochar will affect crop productivity. Here, students conduct an analogous experiment in which they ask the question “How does biochar affect plant growth in different soil types?”
Prompt students to make a prediction about whether biochar will
increase, decrease, or have no effect on plant growth and to explain
their ideas about why (Appendix 2). Ask them to list the dependent
variables they would measure in order to answer this question
(Appendix 2). Variables may include plant height, plant biomass,
stem diameter, and number of leaves, among others. Scientists typically assess crop productivity by measuring plant height and aboveground (shoot) and belowground (root) biomass, and compare the
amount of biomass plants have allocated to roots in relation to total
plant biomass (root mass ratio). Students could measure plant height
and aboveground and belowground biomass, and other variables
that emerge from your classroom discussions.
• Pots with holes at the bottom (3 in2 [7.6 cm2] recommended)
• Window screen mesh
• Commercial potting soil (fill to 80% volume of the pot)
• Topsoil (collected locally; fill to 80% volume of the pot)
• Sand (fill to 80% volume of the pot)
• Biochar (10% by volume)
Table 1. Properties of biochar from different feedstocks, including surface area, total carbon, and pH. Values
are taken from research studies that incorporated different biochars into soils. Values vary depending on
Agricultural crop Corn stovera 550 12 74.3 9.89
Wheat strawb 200 2.53 38.7 5.43
Wheat strawb 350 3.48 59.8 8.69
Wheat strawb 500 33.2 62.9 10.2
Pinec 400–700 232.72 72 9.2
Grassb 500 3.33 62.1 10.2
300 1.3 66.2 7.9
Algaee 305 1.15 28.9 8.0
Animal waste Cow manureb 500 21.9 43.7 10.2
Pig manureb 200 3.59 37.0 8.22
Pig manureb 350 4.26 39.1 9.65
Pig manureb 500 47.4 42.7 10.5
aFuertes et al. (2010).
bZhao et al. (2013).
cFoster et al. (2016).
dSun et al. (2014).
eBird et al. (2011).