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There is renewed interest in fodder beet (Beta vulgaris L.) production in the South Island of New Zealand. However, recommended agronomic practices for maximising productivity and quality are limited. Two experiments investigating the effects of different rates (kg/ha) of potassium (K; 150 or 300), sodium (Na; 100 or 200) and chloride (Cl; 240) fertiliser application on fodder beet dry matter (DM) production, nutrient concentration and uptake were carried out at Southbridge (2011) and Bankside (2012), Canterbury, New Zealand. Final DM yield was unaffected by the treatments: averaging 32 t DM/ha at Southbridge and 21 t DM/ha at Bankside. However, there was a significant interaction between K and both Cl and Na, on DM yield at Southbridge. Specifically, yield increased to 38 t DM/ha with Na and decreased to 30 t DM/ha with Cl, in the presence of K. Application of K, Na, and Cl fertiliser increased the respective tissue mineral concentration and respective total uptake for both the bulb and shoot components. Potassium tended to depress crude protein, neutral detergent fibre and ash content of the bulbs and increase the metabolisable energy and soluble sugar. The combination of low fibre and high soluble sugar concentrations puts animals at risk of rumen acidosis. These results suggest that fodder beet crops subjected to high rate of soil and/ or fertiliser K should be supplemented with feed high in crude protein and fibre. Key words: Beta vulgaris L., agronomic practices, mineral concentration, mineral uptake, quality attributes.

North Otago soils are all of sedimentary origin but range in topography from flat alluvial and terrace soils to hill soils. Most of the farmed soils are yellow-grey earths on the rolling downlands or plains. Yellow-grey earths on the downlands have dense subsoils that limit water movement during wet winters and rooting depth during dry summers. Plains soils have shallow depths to gravels limiting water holding capacity and making irrigation necessary for intensive pastoral production. The relationships between soil nutrient levels and pasture production has been shown to be of the diminishing returns type. Soil nutrient levels for near maximum pasture production on North Otago soils are Olsen P 20-25, sulphate-S 10-12, organic-S 15-20 and quick test K 5-8. At high stocking rates profitable responses in pasture and animal production can still be gained at higher Olsen P levels. The decision support nutrient model (OUTLOOKTM) has been developed to help farmers apply fertiliser at optimum rates for economic production. Keywords: economic production, North Otago, phosphorus, potassium, sedimentary soils, sulphur, yellow-grey earths

The generally strongly weathered, leached soils of Northland consist of four major soil groups. The yellow-brown earths and podzols and yellow brown sands are formed from sedimentary rocks, while brown granular clays and red and brown loams are formed from volcanic rocks. In terms of the relationship between pasture production and fertiliser nutrient requirements, for both sedimentary and volcanic soils, the production functions are shown to be of the "diminishing returns" type, and the point at which near-maximum production (97%) occurs is defined as the "biological optimum" soil test level. Biological optimum test values for sedimentary and volcanic soils are: Olsen P 20 and 22; quicktest K 6 and 7; sulphate-S 10; organic-S 15; and pH 5.9. Once biological optimum soil test levels have been attained then maintenance fertiliser nutrient rates are appropriate. In order to move up the pasture production curve an average of 7 and 11 kg P/ha above maintenance will increase Olsen P by 1 unit for Northland sedimentary and volcanic soils respectively. Similarly, on average 60 kg K/ha will raise quicktest K by 1 unit on volcanic soils, but capital requirements for K on sedimentary soils in Northland are not known. An average of 35 and 25 kg S/ha will correct S deficiencies on sedimentary and volcanic soils. Keywords: biological optimum, lime, Northland, nutrient requirements, phosphorus, potassium, sedimentary soils, sulphur, volcanic soils

The soils of North Canterbury occur mainly on steep land (31%), hilly land (28%), rolling downs and downlands (11%) and terraces and floodplains (30%). Most soils are predominantly formed from greywacke and tertiary sediments and some 85% comprise yellow-grey earth, yellow-grey earth to yellow-brown earth intergrade, yellow-brown earth and recent soil groups. In terms of the relationship between pasture production and fertiliser nutrient use these major soil groups are considered as a single entity, namely "sedimentary" soils (a reference to their derivation from sedimentary rocks). The relationships (production functions) between pasture production and soil test level for sulphur (S), phosphorus (P) and potassium (K) are shown to be of the "diminishing returns" type for the sedimentary soils and the point at which near-maximum production (97%) occurs is defined as the "biological optimum" soil test level. Biological optimum sulphate-S and organic-S levels-are-l.0 and 15 respectively, for O-l.s-en- P. -is _ 20 and quick-test K is 6. Once the biologrcal optimum soil test levels have been attained then maintenance fertiliser nutrient rates are appropriate. In order to correct S deficiency sedimentary soils require an average of 35 kg S/ha. To move up the pasture production curve an average of 5 kg P/ha above maintenance will increase Olsen P by 1 unit. Potassium requirements depend on soil group within the sedimentary soils. -Keywords:~biological~optimum, North Canterbury, nutrient requirements, phosphorus, potassium, sedimentary soils, Sulphur