29 Oct 2014

Results from Capella (wheat) and Gindee (chickpea) - 2013.

Response to residual K from bands applied in 2011

Poor patches in wheat due to low K

2013 Field Experiments
The Capella site was sown to wheat in May 2013 following a chickpea crop in 2012. The crop was established over the base treatments laid down before the 2012 crop and no further fertilizer was added. The seasonal conditions at both Capella and Gindee were very dry, with May to October rainfall at Emerald of 76 mm compared to a long-term average of 181 mm.

The Gindee site was sown to wheat in winter, 2013 following a failed sorghum crop sown in January 2013. This site showed that in biomass (Figure 1) unless K was present, minimal responses to P were evident. Fixing K with out fixing P gave 35% growth improvements, but the combination of P and K gave 75%. The Capella site showed the opposite, where the first response was to P, then there was an additive effect of K with P. These soil K levels are the lower at Gindee and while the soil P level is the lower at Capellla, so the order of P and K responsiveness in a responsive crop like chickpea picks up those differences in relative availability.

Figure 1. Grain yield response to chickpea (2012) and wheat (2013) to P, K and S alone and in combination at Gindee, central Queensland.

Summary from Gindee:

¥ Main response to deep P, with a slight trend for an additional benefit of K once P adequate
¥ Lack of in-crop rain (2o roots and tillers) limiting responses in 2013 wheat?
¥ Additional crop production (2012 chickpea @$550/t; 2013 wheat at $275) worth $310/ha for P only, or $380/ha for P+K.
¥ Compared to commercial practice in 2012, deep P provided 900 kg yield benefit (deep tillage + P), lifting combined benefits to $600/ha
¥ Residual value excellent so far. How long will it keep performing?

Figure 2. Grain yield response to sorghum (2012) and chickpea (2013) to P, K and S alone and in combination at Capella, central Queensland.

Summary from Capella:

¥ Response varied with crop - only P in sorghum, but (K + P) in chickpea
¥ Unless K present there was no P response in chickpea
¥ Lack of in-crop rainfall enhancing the value of deep K in 2013?
¥ Additional crop production (2012 sorghum @$200/t; 2013 chickpea at $375) worth $160/ha for P only, or $320/ha for P+K.
¥ Residual value excellent so far. How long will it keep performing?

K Uptake in response to deep placed banded K

CAPELLA SITE – 2011-2013 dry matter and K uptake.
2012 Chickpea; 2013 Wheat