Modelling the effects of row configuration on sorghum yield reliability in north-eastern Australia

Abstract

In recent years, many sorghum producers in the more marginal (<600 mm annual rainfall) cropping areas of Queensland and northern New South Wales have used skip row configurations in an attempt to improve yield reliability and reduce sorghum production risk. This paper describes modifications made to the APSIM sorghum module to account for the difference in water usage and light interception between alternative crop planting configurations, and then demonstrates how this new model can be used to quantify the long-term benefits of skip sorghum production. Detailed measurements of light interception and water extraction from sorghum crops grown in solid, single and double skip row configurations were collected from on-farm experiments in southern Qld and northern NSW. These measurements underpinned changes to the APSIM-Sorghum model so that it accounted for the elliptical water uptake pattern below the crop row and the reduced total light interception associated with skip row configurations. Long-term simulation runs using long-term weather files for locations near the experimental sites were used to determine the value of skip row sorghum production as a means of maintaining yield reliability. These simulations showed a trade-off between long-term average production (profitability) and annual yield reliability (risk of failure this year). Over the long term, the production of sorghum in a solid configuration produced a higher average yield compared with sorghum produced in a skip configuration. This difference in average yield is a result of the solid configuration having a higher yield potential compared with the skip configurations. Skip configurations limit the yield potential as a safeguard against crop failure. To achieve the higher average yield in the solid configuration the producer suffers some total failures. Skip configurations reduce the chance of total failure by capping the yield potential, which in turn reduces the long-term average yield. The decision on what row configuration to use should be made tactically and requires consideration of the starting soil water, the soil’s plant-available water capacity (PAWC), and the farm family’s current attitude to risk.

Morphological and architectural development of root systems in sorghum and maize

“…A narrow root angle may affect the vertical distribution of roots through deeper rooting, which can improve water capture at depth and thus positively affect drought adaptation (Hammer et al 2009;Kato et al 2006;Oyanagi 1994). In contrast, a wider angle favours better lateral access, which could increase water extraction in wide or skip row dryland farming systems (Whish et al 2005). The importance of root angle thus depends on the environmental and management conditions under which a crop is grown.…”

“…Seminal roots play an important part in initial water and nutrient uptake and establishment of seedlings, whereas nodal roots dominate during the later stages of growth. Studies in sorghum and maize throughout their life cycles indicate that the root system grows into the soil at about 2-3 cm day −1 (Dardanelli et al 1997;Manschadi et al 2008;Robertson et al 1993;Whish et al 2005). Root system development of maize has been relatively well studied compared to that of sorghum, but there has been inconsistency in the nomenclature used for root types in maize.…”

Agronomic responses of grain sorghum to DMPP-treated urea on contrasting soil types in north-eastern Australia

“…DMPP is unlikely to be beneficial where the relative contribution of fertiliser N to total crop supply is low, such as with higher starting mineral N profiles (i.e. typically fallows >12 months, termed 'long fallows') or where crop N demands are likely to be low due to use of moisture conservation techniques such as double skip sowing (Whish et al 2005). Our results also suggest that at application rates <60 kg N/ha, there is currently no benefit in using DMPP.…”

High-yielding traits of heavy panicle varieties under triangle planting geometry: A new plant spatial configuration for hybrid rice in China

“…corn, sorghum, peanut, soybean, wheat and rice). Such techniques can show marked effects on grain yield if there is efficient weed control (Whish et al, 2005;Karlen and Camp, 1985;Gozubenli et al, 2004;Steiner, 1986;Brecke and Stephenson, 2006;Janovicek et al, 2006;Bjarko and Line, 1988;Mahajan and Chauhan, 2011;Phillips and Norman, 1962;Myers and Foale, 1981;Holland and Mcnamara, 1982). Low-tillering crops, such as corn and sorghum, see a consistent effect of row configuration.…”