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.
- · 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! | DM | Grain yield | %P | Puptake (kg/ha) | %K | Kuptake (kg/ha) | S (mg/kg) | Suptake (kg/ha) |
Farmer ref | 4671 | * | 0.13 | 6.0 | 1.31 | 61.4 | 1025 | 4.8 |
Ctrl | 5150 | 2388 | 0.12 | 6.3 | 1.15 | 59.2 | 1000 | 5.1 |
Ctrl +TE | 4943 | 2318 | 0.12 | 6.1 | 1.16 | 57.8 | 967 | 4.8 |
S | 4817 | 2357 | 0.12 | 5.8 | 1.16 | 55.6 | 1017 | 4.9 |
K | 4915 | 2386 | 0.12 | 5.8 | 1.38 | 68.1 | 983 | 4.8 |
K:S | 5350 | 2348 | 0.11 | 5.7 | 1.29 | 68.6 | 917 | 4.9 |
P | 6023 | 2782 | 0.15 | 9.2 | 1.14 | 68.6 | 1033 | 6.2 |
P:S | 5837 | 2806 | 0.15 | 8.6 | 1.12 | 64.9 | 1033 | 6.0 |
P:K | 6903 | 2899 | 0.15 | 10.1 | 1.51 | 104.2 | 1000 | 6.9 |
P:K:S | 6987 | 2808 | 0.16 | 10.8 | 1.50 | 105.1 | 1083 | 7.6 |
P:K:S +TE | 6452 | 2832 | 0.16 | 10.3 | 1.54 | 99.5 | 1117 | 7.2 |