Hydrolysed wool: a novel soil amendment for zinc and iron biofortification of wheat

Figures & data

Table 1  Selected properties and trace element concentrations of the soil used in the experiments.

	Value
Parameter	Mean	Median
Texture^1
Clay (%)	4.2	4
Silt (%)	19.5	19.4
Sand (%)	76.3	76.6
pH (CaCl2)^2	7.08	7.1
Organic matter content (%)^3	1.4	1.4
CaCO3 content(%)^4	9.6	9.7
Max. water holding capacity (%)	41	39.8
Electrical conductivity (µS cm^−1)^5	72.3	69
C/N-ratio^6	14.5	14.3
Total P-content (mg kg^−1)	1230	1234
Total S-content (mg kg^−1)	504	512
NaNO3 extractable TE (mg kg^−1)^7
Zn	0.24	0.23
Fe	17.4	17
Total TE ^8
Zn (mg kg^−1)	60.6	60
Fe (g kg^−1)	21.5	21.2
^1The soil texture was determined according to pipette method (KOM—FAL et al. [1996]) with n=5.
^2The pH was determined according to DIN ISO 10390 in 0.01M CaCl2 with n=5.
^3The organic carbon content was determined by oxidation using potassium dichromate according to FAL et al. (1996) with n=5.
^4Total carbonate content was determined volumetrically (measurement of the CO2 volume released through reaction with HCl), according to FAL et al. (1996) with n=5.
^5The electric conductivity was determined in an aqueous soil extract according to DIN ISO 11265 with n=5.
^6Total carbon content as well as total nitrogen content were measured by dry combustion using a CNS-2000 Analyser (Leco, US-Saint Joseph, Michigan) with n=5.
^7NaNO3 extractable TE were determined via ICP-OES according to FAL et al. (1996) with n=3.
^8Total TE content was determined via X-Ray Fluorescence Spectrometry (Spectro-X-lab 2000, Germany) with n=3.

Table 2  Composition (in mg L⁻¹ WH and mg kg⁻¹ of wool) and pH of wool hydrolysate used in the experiments (n=3).

	(mg L^−1 of WH)		(mg kg^−1 of wool)
Character	Min.	Max.	Min.	Max.
Kjeldahl nitrogen^1	837	1520	20925	38000
Sulphur^2	3430	12800	85750	320000
Trace elements^2
Zn	1.76	2.5	44	62.5
Fe	0.19	0.23	4.75	5.75
Cu	b.d.	b.d.	b.d.	b.d.
K	12.45	28.37	311.25	709.25
Ca	15.9	26.68	397.5	667
Na	186	1252	4650	31300
	Value
	Min.	Max.
pH	6.2	6.3
^1 Total nitrogen determination was carried out at Bachema (CH-Schlieren) using Kjeldahl analysis.
^2 Total sulphur and TE content of the WH was determined via ICP-OES using an external calibration.
Note: b.d.=below detection.

Figure 1  Relationships between added amount of WH per kg soil and NaNO₃ extractable soil Zn (A, ○) and Fe (B, ○). • corresponds to the amount of TE added to the soil with the WH solution per kg of soil.×represents the TE concentration that would be expected to result from TE-free WH addition. Error bars represent±standard deviation of triplicates (n=3).

Figure 2  Mean grain versus shoot dry weight per plant of the controls (C), a treatment with the same elemental composition (MF) as in the WH and the WH treatment. Different letters indicate statistically significant difference (P<0.05). Error bars represent±standard deviation of four replicates (n=4).

Figure 3  Mean Zn and Fe concentrations in grains (A) and shoots (B) of the controls (C), a treatment with the same elemental composition (MF) as in the WH and the WH treatment. Different letters indicate statistically significant difference (P<0.05). Error bars represent±standard deviation of four replicates (n=4).

Figure 4  Relationship between Zn (○) and Fe (•) concentrations and protein content in the grains, determined using a N:protein conversion factor (Mosse 1990).

FAL, RAC, FAW 1996 . Extraktion von Schwermetallen mit Natriumnitrat (1:2.5) . Schweizerische Referenzmethoden der Eidgenössischen landwirtschaftlichen Forschungsanstalten. Eidgenössische Forschungsanstalt FAL, RAC, FAW .

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Mosse , J . 1990 . Nitrogen to protein conversion factor for 10 cereals and 6 legumes or oilseeds. A reappraisal of its definition and determination. Variation according to species and seed protein content . Journal of Agriculture and Food Chemistry , 38 : 18 – 24 . doi: 10.1021/jf00091a004

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