**Vis/Near- and Mid- Infrared Spectroscopy for Predicting Soil N and C at a Farm Scale**

Haiqing Yang1 and Abdul M. Mouazen2

*1College of Information Engineering, Zhejiang University of Technology, Hangzhou 2School of Applied Sciences, Cranfield University, Bedfordshire 1P.R. China 2United Kingdom* 

### **1. Introduction**

184 Infrared Spectroscopy – Life and Biomedical Sciences

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Vis/Near- and Mid- Infrared Spectroscopy for Predicting Soil N and C at a Farm Scale 187

b mixture of Cambisol and Luvisol types.

**2.2 Reference methods** 

Table 1. Description of the five targeted farm fields

Code Field Name Vegetation Soil type Sand

Fig. 1. Location of the five fields targeted in the study (www.landis.org.uk)

a according to USDA triangular diagram relating particle size distribution to soil texture.

whereas the majorities were left for spectrophotometer measurement.

Finally, IC was calculated by the difference between TC and OC.

(%)

A Avenue Ground wheat C+Lb 61.9 20.1 18.1 Sandy loam B Orchard wheat Cambisol 40.1 27.4 32.5 Clay loam C Ivy Ground Soybean Cambisol 21.1 27.2 51.7 Clay D Showground wheat Luvisol 65.0 20.9 14.1 Sandy loam E Copse Field wheat Cambisol 14.6 27.8 57.6 Clay

of soil texture classification. Soil samples were air-dried and crushed at first. Plant residues and stones were then removed. After that, the samples were sieved to pass a 2 mm mesh and air-dried again at 40℃ for 48h. A small amount of soil was used for chemical analysis,

Particle size distribution was determined by a combination of wet sieving and hydrometer tests using the USDA soil texture classification system. Reference values of N and C were analyzed through a sequence of processes. First, a 50 mg sample was used for the measurement of TN and TC by a TrusSpecCNS spectrometer (LECO Corporation, St. Joseph, MI, USA) using the Dumas combustion method. Next, another 50 mg from each soil sample was mixed with 5% HCl and then oven-dried at 90℃ for 4 h in order to remove IC. Then, OC in IC-free samples were measured by the same Dumas combustion method.

Silt (%) Clay

(%) Soil texturea

2010), attention is being given to possible alternatives such as Vis-NIR and/or MIR spectroscopy. Numerous analyses of soil N and C have been conducted during the past decades using this technique, for examples, to predict the soil C and N mineralization rates (Fystro, 2002; Mutuo*, et al.*, 2006), to derive spectral characteristics for classifying conventional and conservation agricultural practices (Haché*, et al.*, 2007), to assess soil changes due to site disturbance during forest harvesting (Ludwig*, et al.*, 2002), to evaluate the recovery of microbial functions during soil restoration (Schimann*, et al.*, 2007), to determine carbon inventories (Reeves III*, et al.*, 2002), to determine (*in situ*) organic matter composition of coatings at crack surfaces and linings of earthworm burrow walls (Reeves III*, et al.*, 2002) and others (Chang*, et al.*, 2001; Chang & Laird, 2002; Yang*, et al.*, 2011a).

