The Response of Crops to Potassium Placement Depth and Band Spacing

The right place for K in summer dominant rainfall areas of northern Australia.

IPNI-2010-AUS-13

24 Jan 2013

2012 Response to K placement - Chickpea, Capella.


Growth and yield
    · Dominant response to P (biomass and grain)
    · Additive effect of K once P supplied in biomass, but not in grain yield.
    · No response to S, alone or in combination with P and/or K.
Nutrient uptake
    · No evidence of any response to added S, in concentration or uptake. Higher S uptake occurs when P, and to a lesser extent Pand K, are added. Once both P and K are adequate, there seems to be some response to S in terms of %S in DM, but it is small. This is surprising, considering the low profile S (1 site excepted) and low organic matter.
    · Responses to added K are evident, but small considering the 200 kg K/ha that was added! There is a sig increase in %K when K is added without P, but it is pretty small - certainly not indicative of luxury uptake! When P is added without K, biomass concentrations remain low (same as Control), but extra K is extracted from the profile - presumable due to the better root system and more thorough profile exploration. In fact, K uptake is about the same as where K is added without P. However, when K is added with P we see K uptake increasing by about 70%...driven by both higher %K in biomass and improved growth response.
    · Similar responses are observed with added P. Concentrations in biomass increase with added P (despite stronger growth), and are slightly higher again when PKS are added together. Adding P alone increases P uptake by about 50%, and adding P and K increases this to about 75%, as with K.
Id!DMGrain yield%PPuptake (kg/ha)%KKuptake (kg/ha)S (mg/kg)Suptake (kg/ha)
Farmer ref4671*0.136.01.3161.410254.8
Ctrl515023880.126.31.1559.210005.1
Ctrl +TE494323180.126.11.1657.89674.8
S481723570.125.81.1655.610174.9
K491523860.125.81.3868.19834.8
K:S535023480.115.71.2968.69174.9
P602327820.159.21.1468.610336.2
P:S583728060.158.61.1264.910336.0
P:K690328990.1510.11.51104.210006.9
P:K:S698728080.1610.81.50105.110837.6
P:K:S +TE645228320.1610.31.5499.511177.2