Issues in using Land Use Capability class to set nitrogen leaching limits in moisture-deficient areas—a South Island case study

Figures & data

Figure 1. Components of the Land Use Capability classification (source: Lynn et al. 2009).

Figure 2. Increasing limitations to use and decreasing versatility of use from LUC Class 1 to LUC Class 8 (modified from SCRCC [1974]). † includes vegetable cropping (source: Lynn et al. 2009).

Table 1. Reproduction of table 13.2 of the Decision Version of the One Plan^a with reducing Class limits over a 20-year period (Horizons Regional Council 2014).

Nitrogen leaching maximum (kg/ha/yr)	LUC Class
	1	2	3	4	5	6	7	8
Year 1	30	27	24	18	16	15	8	2
Year 5	27	25	21	16	13	10	6	2
Year 10	26	22	19	14	13	10	6	2
Year 20	25	21	18	13	12	10	6	2

^a http://www.horizons.govt.nz/about-us/one-plan/.

Table 2. Estimates of NZLRI attainable stock-carrying capacities for LUC Classes mapped in the Canterbury Region under rain-fed agricultural conditions (from Hunter et al. [1980] and Van Berkel [1983]).

LUC Class	Attainable stock-carrying capacity (su/ha)^a
	Maximum	Mean	Minimum	Gross difference
Arable land
1	22	20	18	4
2	20	18	16	4
3	24	15.5	10	14
4	19	11.6	5	14
Non-arable land (assessed under perennial vegetative cover)
5	13	10	4.5	8.5
6	14	8.3	2	12
7	10	3	0.1	9.9
8
Unsuitable for sustained pastoral production	0	0	0	0

^aOne stock Unit is equivalent to a breeding ewe (55 kg at mating) rearing one lamb.

Table 3. Estimates of NZLRI attainable stock carrying capacities for LUC Class and LUC Subclasses mapped in the Canterbury Region under rain-fed agricultural conditions (derived from Prickett [1978] and Van Berkel [1983]).

		Attainable stock-carrying capacity (su/ha)^a
LUC Class	LUC Subclass	Maximum	Mean	Minimum	Gross difference
Arable land
1	w	22	–	–	–
	s	–	–	–	–
	c	18	–	–	–
2	e	17	16.5	16	1
	w	20	–	–	–
	s	20	17.6	16	4
	c	20	18.5	17	3
3	e	18	14.8	10	8
	w	18	17.3	17	1
	s	17	14	10	7
	c	24	20	16	8
4	e	17	11.8	7	10
	w	13	12.5	12	1
	s	19	10.8	5	14
	c	15	13	11	4
Non-arable land (assessed under perennial vegetative cover)
5	e	–	–	–
	w	13	10.5	8	5
	s	11	9.3	4.5	6.5
	c	10	–	–	–
6	e	14	8.8	2	12
	w	8	–	–	–
	s	10	6.4	4	6
	c	4	3.5	3	1
7	e	10	3.1	0.2	9.8
	w	9	–	–	–
	s	6	1.9	0.1	5.9
	c	4	2.25	0.5	3.5
8	Unsuitable for sustained pastoral production

^aOne stock Unit is equivalent to a breeding ewe (55 kg at mating) rearing one lamb.

Table 4. Variability in nitrate storage and reduction, and hence relative nitrate leaching, for a sequence of soils within LUC Class 3, on the eastern plains (adapted from Hewitt et al. [2015]).

LUC Class	3w1^a	3c1	3e5	3s2	3s9
Representative soil family	Flaxton	Waimakariri	Barrhill	Eyre	Rangitata
Soil type	Deep silt loam	Deep silt loam	Moderately deep silt loam	Shallow silt loam	Stony silt loam
NZ Soil Classification^b	Orthic Gley	Recent	Pallic	Recent	Recent
Depth to >35% stones (cm)	100	100	70	35	0
PAW (mm)	220	206	148	76	46
Drainage Class	Poor	Well	Well	Well	Well
Soil natural capital estimate (by stock adequacy %)^c
Nitrate storage	100	100	32	32	4
Nitrate reduction	42	0	0	0	0

PAW, profile available water.

^aFrom Prickett (1978) and Van Berkel (1983).

^bHewitt (2010).

^cFrom Hewitt et al. (2015).

Figure 3. Potential carrying capacity values found in the Selwyn-Waihora Zone. Diamond (blue) and triangle (green) symbols are the rain-fed values; triangles (green) indicate the dryland values for irrigable LUC (land use capability) units and square symbols (red) show their corresponding irrigated carrying capacity. Diamond (blue) symbols indicate LUC units that are not irrigable.

Table 5. Area in hectares of LUC Classes 1–8, estuaries, lakes, quarries, rivers and towns in the Canterbury Region and nationally as mapped during the NZLRI survey, 1975–1999.

	Canterbury Region^a (×100 ha)	Canterbury Region (%)	NZ total^a (×100 ha)	NZ^a (%)	Total arable and non–arable land in the Canterbury Region (×100 ha and percentage of NZ^a)
LUC Class 1	232	0.5	1870	0.7
LUC Class 2	2705	5.8	12,020	4.5
LUC Class 3	5430	11.5	24,423	9.2	Arable land LUC Classes 1–4
LUC Class 4	5204	11.1	27,773	10.5	13,571 (5.1%)
LUC Class 5^b	24	0.5	2109	0.8
LUC Class 6	11,746	25	74,730	28.1	Non–arable land LUC
LUC Class 7	7296	15.5	56,894	24.1	Classes 5–8
LUC Class 8	11,775	25	58,007	21.8	3,106,068 (11.7%)
Estuaries	32	–	337	–
Lakes	566	1.2	3336	1.3
Quarries	0	–	11	0.0
Rivers	1593	3.4	2739	1.0
Towns	168	0.4	1465	0.6
Total	47,043		265,706

^aExcludes land not mapped as part of the national NZLRI survey such as outlying islands and Stewart Island.

^bClass 5 as mapped under the former SCRCC (1974) definition.

Figure 4. Mean potential livestock carrying capacity under rain-fed and irrigated pasture agriculture for LUC Class 1–8 land.

Table 6. Nitrogen loss limits (kg/ha) for the Selwyn-Waihora Zone calculated using the irrigated and rain-fed productivity indices.

LUC Class	Nitrogen loss limit (irrigated productivity)	Nitrogen loss limit (rain-fed productivity)
1	24.4	29.6
2	23.9	25.9
3	21.6	20.9
4	16.1	15.6
5	16.1	15.6
6	12.0	12.3
7	3.25	2.7
8	0.4	0.4

Lynn IH, Manderson AK, Page MJ, et al. 2009. Land use capability survey handbook—a New Zealand handbook for the classification of land. 3rd edition. Hamilton: AgResearch; Lincoln: Landcare Research; Lower Hutt: GNS Science.

 Google Scholar

SCRCC. 1974. Land use capability survey handbook: a New Zealand handbook for the classification of land, produced for the soil conservation and rivers control council. Wellington: Water and Soil Division, Ministry of Works.

 Google Scholar

Horizons Regional Council. 2014. Proposed one plan as amended by environment court decisions. Palmerston North: Horizons Regional Council; [cited 2014 Feb]. Available from: http://www.horizons.govt.nz/about-us/publications/about-us-publications/one-plan/proposed-one-plan/.

 Google Scholar

Hunter GG, Lynn IH, Prickett RC. 1980. South Island agricultural production estimates for land use capability units. Report No. WS375. Christchurch: Water and Soil Science Centre, Ministry of Works and Development.

 Google Scholar

Van Berkel P, editor. 1983. The South Island land use capability extended legend for the New Zealand land resource inventory. 2nd edition. Wellington: National Water and Soils Conservation Organisation.

 Google Scholar

Prickett RC. 1978. New Zealand land resource inventory South Island land use capability extended legend. Wellington: National Water and Soil Conservation Organisation.

 Google Scholar

Hewitt A, Dominati E, Webb T, Cuthill T. 2015. Soil natural capital quantification by the stock adequacy method. Geoderma. 241–242:107–114. doi: 10.1016/j.geoderma.2014.11.014

 Web of Science ®Google Scholar

Hewitt AE. 2010. New Zealand soil classification. Landcare Research Science Series 1. 3rd edition. Lincoln: Manaaki Whenua Press.

 Google Scholar