The growth and phenology of white wax scale, Gascurdiu destructor (Newstead), and Chinese wax scale, Ceroplastes sinensis del Guercio, infesting Valencia orange (Citrus sinensis (L.) Osbeck), were influenced by nitrogen content but not by other nutrients.

Symptoms observed in maize seedlings growing in the field in the Taree district were reproduced in glasshouse trials. The condition was prevented by applying sodium molybdate to the soil. Grain from certain growers of certified hybrid maize seed produced seedlings susceptible to the deficiency whereas grain from other growers produced seedlings which showed no symptoms. The differences in susceptibility were found to be related to the molybdenum content of the grain which varied from more than 0.40 p.p.m. to less than 0.01 p.p.m. No case of symptoms was observed in seedlings where grain contained more than 0.08 p.p.m. Severe symptoms occurred where grain molybdenum was less than 0.02 p.p.m. Molybdenum applications to female parent rows in seed crops raised the molybdenum content of grain, and prevented or reduced the incidence of symptoms in seedlings grown from this grain.

No abstract

Brimstone, of three different particle size gradings, was compared with finely powdered gypsum in a three year study, on a white clover pasture. Dry matter yield and sulphur recovery were highest ,from gypsum in the first harvest, but brimstone sulphur gave better residual effects. Fineness of grinding influenced the initial availability of brimstone sulphur. The possibility of using particle size gradings to obtain a degree of controlled availability in sulphur fertilizer is discussed in relation to graziers' present and possible future demands. In mixtures of elemental sulphur with soluble sulphate, fertilizers, for example sulphur-fortified superphosphate, a limited amount of delayed release from the elemental sulphur could spread the response over a longer period.

The long-term, annual application of nitrogen (N), phosphorus (P), and potassium (K) to the drip area of Valencia orange trees growing in a Tiltao sandy loam soil in the Sunraysia district of the lower Murray was investigated for its effect on soil pH, Bray 1 extractable soil P, and exchangeable cations calcium (Ca), magnesium (Mg), K, sodium (Na), and aluminium (Al) at 5 soil depths.Nitrogen (applied as ammonium nitrate) generally lowered soil pH to a depth of 30 cm, the effect increasing with rate of applied N. At 20 cm depth, the highest rate of applied N (450 kg/ha) reduced soil pH from 7.6 to 3.9, while 150 kg N/ha resulted in a soil pH of 5.0. Consequently, levels of exchangeable Ca, Mg, K, and Na in the soil were lower. There was a strong negative correlation between soil A1 and soil pH. At soil depths of 10-30 cm, the highest rate of applied N resulted in high levels (>20%) of exchangeable A1 as a proportion of the effective cation exchange capacity (CEC). Available soil P increased with rate of applied P, but the effect decreased with depth. Significantly (P<0.05) increased levels of available P were found to 30 cm depth when P was applied at 30 and 90 kg/ha, and to 60 cm depth at 180 kg P/ha. At 180 kg P/ha, Ca from superphosphate decreased Mg to 60 cm depth. Soil K levels were higher with increased rate of applied K and increased soil depth. The highest rate of applied K (360 kg/ha) depressed available P to 90 cm depth. Exchangeable Mg, K and Na percentages of the CEC in most treatments and at most soil depths were above the desirable range. Soil Na levels for some treatments and depths approached the level for sodic soils.