What do pulses contribute to the nitrogen balance in Central Queensland farming systems

Take home message • Nitrogen derived from atmosphere (Ndfa) in mungbean crops is strongly influenced by the amount of mineral soil nitrates that are available at planting. There is an almost linear decline in N2 fixation as soil nitrates increase in the top 60cm of the profile. • Mungbean and chickpea crops can access and utilise soil nitrate N in the top 60cm as efficiently as cereal crops. This raises implications for nitrate N supply in crops following these pulse crops. • Mungbeans planted in long fallow situations will create a soil nitrate N deficit as N2 fixation rates cannot replace the amount of soil nitrate being exported in grain. Circumstantial evidence suggests that chickpeas may be similar

Fine tuning deep phosphorus and potassium management

Take home message • The re-application interval for the deep placement of phosphorus (P) and potassium (K) will depend on the most limiting nutrient and crop type • Residual effects of deep P bands applied 5 years previously were still evident in the 2019 chickpea crop on a site with very low soil P status, with yield increases of 500 (20P) to 1000 (40P) kg/ha compared to sites where no deep P had been applied • However, yield increases of a further 900 kg/ha were recorded when a 2nd deep P application was made during the preceding fallow, clearly augmenting the P supply from the residual P bands • In contrast, there was no evidence of any residual benefits from deep K bands applied 3-5 years ago shown in chickpea crops at two low K sites, but yield increases of 500 kg/ha were recorded when K was re-applied during the preceding fallow • Potassium-limited sites may require shorter re-application intervals than sites where the main limit is phosphorus • Legume grain crops export more K/t grain than cereals, but cereals can quickly redistribute deep K back to surface soil layers in stubbles, due to their low rates of removal

Nutritional strategies to support productive farming systems

Take home messages • A critical success factor for cropping systems that rely heavily on stored soil water is co-location of plant nutrients with moist soil and active roots • Our current fertiliser management practices need refinement, with low efficiency of fertiliser recovery often associated with nutrients and water being in different parts of the soil profile • There needs to be greater consideration of placement and timing of fertiliser applications to improve fertiliser nutrient recovery • Declining native fertility reserves means more complex fertiliser combinations will be needed to meet crop demand

Strategies to improve efficiency of use of applied N, P and K fertiliser in Central Queensland

Take home messages • Available moisture has been the main limit to productivity in recent seasons but using that water efficiently to produce harvestable yield is impossible without adequate nutrients • The background nutrient status of soils in Central Qld is variable, but there is an increasing reliance on fertilisers to meet the demands of both cereal grains and pulses • With more $/ha invested in fertilisers, comes a need for efficient use of that fertiliser to ensure there is a return on that investment • A common cause of low efficiency of fertiliser recovery in cereal and legume crops is that nutrients and water are increasingly located in different parts of the soil profile • There needs to be greater consideration of fertiliser placement, product and timing to improve fertiliser nutrient recovery, and strategies need to be based on a solid understanding of the interactions between crop root systems, soil characteristics and nutrient dynamics against a background of variable seasonal moisture availability

Deep P and K - Outcomes from 8+ years of research: the good, the bad and the ugly

Take home messages • Stratified soil testing guides fertility and constraint identification. These tests do not need to be conducted annually for immobile nutrients and constraints • Research experiments with subsurface placement of fertiliser phosphorus (P) at around 20-25 cm on low Colwell P subsoil tests has significantly increased grain yield in central Queensland (CQ) across range of wheat, chickpea and sorghum crops. Winter cereals across southern Qld are generally also positively responding, but chickpeas and sorghum responses in this region have been mixed, ranging from positive to no effect. Data for northwest slopes and plains of NSW is very limited • The relationships between crop P uptake and grain yield for chickpea, wheat and sorghum are robust. As you get more P into the plant, yields are increasing • Potassium is an emerging yield constraint, but data sets are not yet as extensive as for P

Deep P bands – the solution to subsoil decline or just a useful supplement?

Increasing removal of phosphorous (P) via grain harvests, shallow fertiliser placement and direct drill tillage systems have collectively produced soil P profile distributions that are strongly stratified and increasingly deficient in subsurface layers. Nutrient supply in these layers is a critical success factor for cropping systems that rely on stored soil moisture. Banding of P fertilisers into the 10-30cm profile layer has produced strong crop yield responses in Vertosols in CQld, particularly in seasons where topsoils are dry for extended periods. The relationship between P uptake and grain yield is typically linear, with little evidence of luxury P accumulation in either biomass or grains. We hypothesize that root proliferation around deep P bands rapidly dries these P-rich zones and limits P acquisition unless rain events are large enough to rewet those profile layers. While residual fertiliser benefits are strong, crops are still reliant on declining indigenous P reserves to achieve water-limited yield potential

Nitrogen cycling and management decision making in Central Queensland farming systems – N availability and recovery across the farming system – N impacts on productivity – implications for management in CQ

Take home messages The nitrogen (N) fertiliser demand for cereal cropping systems can increase due to two factors: 1. A reduction in the amount of soil organic N mineralised due to the continued decline of natural capital (soil organic carbon and total nitrogen) that occurs under cropping; and 2. An increased crop N demand due to higher yield potentials resulting from optimising other components of the cropping system. The amount of biological N fixation by pulse crops (chickpea/mungbean) is related to the crop yield and biomass and the availability of soil mineral N from mineralisation or carry-over of residual fertiliser. Where deep phosphorus (P) and potassium (K) application increases chickpea biomass (and grain yield), there is generally more N fixed. While some of this is re-exported in grain, the greater residue return means more N is carried forward to the next crop. Growers have a selection of fertiliser N management practices that have differing strengths and weaknesses – it is not a one-size-fits-all model for CQ (or northern region) farming systems. The 4R framework allows choice of rate, source, time and place for any nutrient applied to be implemented suiting each growers’ preferences, with on-going research addressing several themes in regional Qld

Can partial reduction of shoot biomass during early vegetative phase of chickpea save subsoil water for reproductive and pod filling?

The present study investigated if partial reduction of shoot dry matter during early vegetative growth phase of chickpea crop (cv. PBA Seamer) saves sub-soil water for reproductive growth and grain filling of the crop grown at 9 diverse environments. The environments were created by a combination of 3 sites (Emerald, Hermitage and Kingaroy), 3 planting windows (environments 1, 2, 3 at each site) with and without supplementary irrigation. The effects of environments on canopy management (partial reduction in shoot dry matter vs control) and irrigation treatments on the water uptake by roots, crop growth and yield performance and yield components were investigated. Crops in the planting windows (EN 1, 2, 3) experienced variable environments at each site. Days to 50% flowering and crop maturity reduced progressively from EN 1 to EN 3 at the three sites. The environment had significant effect on shoot biomass, yield and HI at the three sites (P  0.5 in EN 2 at Emerald. There was a trend for an increase in HI from EN 1 to EN 3 at all sites. The response to Irr, computed as the difference in peak shoot biomass and yield between the Irr and RF treatments, was the highest at Hermitage and the least at Emerald site. Vapour pressure deficit during reproductive phase accounted for the majority of variation in shoot biomass response to irrigation (r2 =0.66, P < 0.001) for total dry matter and (r2 =0.46, P < 0.01) for yield. The environments had a significant effect on radiation use efficiency and water use efficiency and the yield components including hundred seed weight

Grouping practices in the primary school: what influences change?

During the 1990s, there was considerable emphasis on promoting particular kinds of pupil grouping as a means of raising educational standards. This survey of 2000 primary schools explored the extent to which schools had changed their grouping practices in responses to this, the nature of the changes made and the reasons for those changes. Forty eight percent of responding schools reported that they had made no change. Twenty two percent reported changes because of the literacy hour, 2% because of the numeracy hour, 7% because of a combination of these and 21% for other reasons. Important influences on decisions about the types of grouping adopted were related to pupil learning and differentiation, teaching, the implementation of the national literacy strategy, practical issues and school self-evaluation