A scoring system based on the position of the boundary (milkline) between the solid starch phase and the liquid phase on the surface of the maize kernel was evaluated as an indicator of crop stage of maturity. Milkline score (MLS) varies from 0 when the kernel contents are all liquid and no milkline is visible to 5 when the kernel contents are all solid and grain filling is complete. The scoring sytem is continuous in intervals of 0.5 units. The MLS was linearly related to the dry matter (DM) content of the cro in experiments at Nowra (R2 = 0.72), Wagga Wagga (R2= 0.82), and Grafton (R2 = 0.65). The predicted dry matter content at MLS 2.5 was 34.2% at Nowra, 36.0% at Wagga Wagga, and 33.7% at Grafton. Under normal seasonal conditions, milkline scoring can be used by farmers to help decide when their crops are ready for harvest. Crop DM is optimal for silage productions when MLS is in the range 2-3. However, the technique may not be reliable with severely stressed crops. Sampling 10 cobs from an area of 0.25 ha gave a 95% confidence of detecting the MLS with a precision � 0.37 unit. At Nowra the milkline moved down the kernel at a rate of 1 MLS unit/9 days. This rate may be different in other environments. At the same site there was a significant (P<0.05) quadratic relationship between milkline score and DM yield, with maximum yield obtained at MLS 3.4. However, this relationship accounted for only 16.76% of the variation, and clearly, other factors influenced DM yield.

A method is described for estimating the nutrient content of pasture selected by grazing cows. The method is non-invasive and suitable for use on commercial farms. Results from use of the method are reported for studies on a commercial farm over a period of 29 months. Confidence limits were calculated for estimated nutrient contents of pasture eaten. Estimated nutrient contents then were compared with recommended nutrient contents for high-yielding cows. Significant deficiencies of energy, protein, Ca, P and Na were common. Seasonal trends in nutrient content of pasture eaten are reported, together with selection differentials between pasture eaten and pasture available.

Phosphorus (P) as superphosphate was applied at 0, 12, 24, and 48 kg P/ha each year from 1972 to 1980 to an established white clover (Trifolium repens) and carpet grass (Axonopus affinis) pasture, to measure long-term changes in soil fertility and pasture production under grazing on a duplex soil in a coastal, subtropical environment. Hereford weaner steers grazed the pasture at 2 stocking rates (1.67 and 2.5 steers/ha) from 1972 to 1974, and at 3 stocking rates (1.67, 2.50, and 3.3 steers/ha) for 7 years to 1981. The effects of P and stocking rate during 1972-76 on pasture and animal production were small and variable, so the study was extended to 1980-81 to measure longer term P and stocking rate effects on soil fertility. Available soil P (bicarbonate-extracted) and sulfur (S, phosphate-extracted) responded (P<0.05) linearly over time to rates of maintenance superphosphate. For soil P, this effect increased with time and showed seasonal fluctuations, which were described by a model with linear and curvilinear functions. After 9 years, average soil P levels at the 4 rates of applied superphosphate changed from 32 to 12, 24, 45, and 91 mg P/kg soil, respectively. A residual value function (RVF) was used to predict the residual value of applied phosphorus over time, which fitted the observed values of available soil P for each fertiliser treatment (R2 = 0.99). The soil S response to superphosphate remained constant over time. Mean values at the 4 rates of applied superphosphate were 8, 11, 15, and 25 mg/kg. Over the 9 years, total soil nitrogen increased (P<0.01) linearly from 0.134 to 0.179% and pH decreased (P<0.05) slightly from 5.7 to 5.2, but neither was significantly affected by superphosphate application. Total pasture and clover growth measured in cages responded linearly to superphosphate, with maximum (P<0.05) response occurring in spring each year from 1972-73 to 1976-77. It was concluded that on this duplex soil with 32 mg/kg of bicarbonate-extractable P, omitting superphosphate reduced soil P after 12 months and pasture growth within 18 months. Annual applications of superphosphate from 125 to 250 kg/ha (12-24 kg P/ha) maintained bicarbonate-extractable soil P in the range 24-45 mg/kg and improved growth and seed reserves of white clover in this environment.

Maintenance dressings of superphosphate were applied at 500,250, 125 or 0 kg/ha each year between 1972 and 1976 to a carpet grass (Axonopus affinis)-white clover (Trifolium repens) pasture in a subtropical environment at Grafton, New South Wales. The pasture had previously received a total of 1500 kg superphosphate/ha in four annual dressings between 1968 and 1972 and was in the maintenance phase, in contrast to the development phase, of fertilizer requirement. The topdressed pastures were grazed by weaner Hereford steers for 12 months during each of five years 1972 to 1977. Two stocking rates (1 .67 and 2.5 steers/ha) were applied in 1972 to 1974 and three (1.67, 2.5 and 3.3 steers/ha) in 1974 to 1978. The effects of superphosphate maintenance rate and stocking rate on dry matter and nitrogen in the available herbage components were small and inconsistent and suggested large residual effects of previously applied superphosphate. The effect of superphosphate maintenance rate on phosphorus in the available herbage components was more consistent but was also small and did not appear to influence pasture or animal production. Reduced maintenance dressings of superphosphate decreased (P< 0.05) annual liveweight gains of steers during only two of the five years, 1974-75 and 1975-76. The effect, which was small and dependent on stocking rate and seasonal conditions, indicated large residual effects of previously applied superphosphate which could be used to advantage when low beef prices preclude the application of maintenance dressings of superphosphate. Liveweight change was related to available herbage components (P<0.05) but the nitrogen content and digestibility of the herbage selected by cattle fistulated at the oesophagus provided more precise estimates of liveweight change. Superphosphate influenced steer liveweight change through its effect on pasture quality rather than quantity.