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One of the problems which arises when analysing and interpreting results from field trials designed to test the efficacy of fertilisers and fertiliser-type products on pastures and crops is the conundrum of Type 1 and Type 2 statistical errors: is the product having literally no effect, or is the trial not "powerful" enough to detect small differences. This problem can be objectively and pragmatically solved, when sufficient trial data are available, by using cumulative frequency distribution functions. In this paper we explain what cumulative frequency distribution functions are and their usefulness for determining the agronomic effectiveness of products. This technique is then applied to field trial data testing the effectiveness of a number of fertiliser and fertiliser-type products used in agriculture today. It is concluded that this approach provides a more objective basis for determining the efficacy or otherwise of fertilisers. Keywords: fertilisers, agronomic effectiveness, testing, field trials, cumulative frequency distribution.

In the last decade major reviews on the phosphorus (P), potassium (K) and sulphur (S) nutrient requirements of clover-based pastures in New Zealand have been completed. This has resulted in adjustments to the P, K and S pasture production functions and some changes to the critical levels for soil tests, and modifications to our interpretation of some soil tests such as Organic S and Reserve K. Applying this new information to New Zealand's hill country pastoral soils, using case studies, suggests that there is considerable unrealized potential to increase productivity. Keywords: critical levels, economics, fertiliser, pasture, phosphorus, potassium, soil fertility, soil tests, sulphur

Five field trials were conducted over 2 years in which the effects of single applications of different rates of a controlled release nitrogen (N) fertiliser, Smartfert, on pasture production and pasture N concentration were measured, relative to the same rates of SustaiN. The 2016 trials also compared multiple applications of SustaiN with a single application of Smartfert. Pasture responses to SustaiN relative to the control generally occurred within the first one to three harvests following application and then declined and became negative in the later harvests. The pasture responses to Smartfert developed more slowly and were greatest after the third harvest. In terms of total production significant (P

Core Ideas Fixation of fertilizer phosphorus in soils often decreases phosphorus efficiency. Avail has been reported to enhance fertilizer phosphorus efficiency. A review on the effect of Avail on soil phosphorus‐fixation is critically discussed.