Results are presented of two multi-factorial field experiments on permanent pasture with six fertilisers and ground limestone. The trials were carried out at Marton Experimental Area and at Invermay Research Station, Mosgie!. Treatments were: -high versus low rates of ground limestone, muriate of potash, and double superphosphate; and some against nil rates of elemerrta'l sulphur, magnesium carbonate, borax, and sodium molybdate.All treatments except limestone and sodium molybdate were applied annually by 'top-dressing.The main effects and two-factor interactions of these seven treatments on yield, concentration of nutrients in the pasture, herbage composition, and soil quick tests, were determined with considerable accuracy. Yields were affected by negative LMo, LP, LMg, MgP, and LMoB, and by positive LK, SK, and BP interactions. The negative interactions were the results of two or more treatments acting in the same direction. Heavy liming increased the availability of molybdenum and of phosphorus as measured by plant uptake and dry matter yields. Magnesium carbonate slightly raised soil pH and acted simiilarly to lime on molybdenum availability. It did not increase phosphorus concentration in plants, but it increased the yield responses on the low phosphorus plots at Marton. Positive interactions generally resulted from simultaneous corrections of deficiencies or toxicities. At Marton yield responses to muriate of potash were increased by an adequate supply of sulphur and by heavy liming. Borax raised yields occasionaHy on the high phosphate plots, but tended to depress yields on the low phosphate plots. The concentrations of N, P, K, Ca, Mg, Na, Mn, Mo, B, and eu in the pasture were influenced by treatments, many interactions taking place.The results of these trials indicate rhe importance of balancing fertiliser and lime applications correctly to give maximum returns; they also indicate new lines of investigation in the fie1d of soil fertility and pasture growth.
