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

Mutation in the guanine nucleotide-binding protein beta-3 causes retinal degeneration and embryonic mortality in chickens

PURPOSE. To identify the gene defect that causes blindness and the predisposition to embryonic death in the retinopathy globe enlarged (rge) chicken. METHODS. Linkage analysis, with previously uncharacterized microsatellite markers from chicken chromosome 1, was performed on 138 progeny of an rge/+ and an rge/rge cross, and candidate genes were sequenced. RESULTS. The rge locus was refined and the gene for guanine nucleotide-binding protein β-3 (GNB3), which encodes a cone transducin β subunit, was found to have a 3-bp deletion (D153del) that segregated with the rge phenotype. This mutation deleted a highly conserved aspartic acid residue in the third of seven WD domains in GNB3. In silico modeling suggested that this mutation destabilized the protein. Furthermore, a 70% reduction was found in immunoreactivity to anti-GNB3 in the rge-affected retina. CONCLUSIONS. These findings implicate the β-subunit of cone transducin as the defective protein underlying the rge phenotype. Furthermore, GNB3 is ubiquitously expressed, and the c.825C→T GNB3 splicing variant (MIM 139130) has been associated with hypertension, obesity, diabetes, low birth weight, coronary heart disease, and stroke in the human population. It therefore seems likely that the defect underlying these human diseases also causes reduced embryonic viability in the rge chicken, making it a powerful model for studying the pathology involved in these associations

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

Phosphorus dynamics in Vertosols: improving fertilizer management

Phosphorus (P) increasingly constrains crop productivity in Australian Vertosols (Australian Soil Classification, Isbell et al., 2021). However, P behaviour and dynamics in Vertosols are still not well understood especially within complex cropping systems. To complement our knowledge in P dynamics in Vertosols and collect critical information as a baseline for future agricultural model development, nine Vertosols were incubated with various P fertilizer treatments. Phosphorus dynamics were modelled in relation to physical and chemical properties. Results indicate that physical and chemical properties and P dynamics of the Vertosols are highly variable and differ substantially from the other soil types. This suggests that inclusion of selected soil properties to current soil P models could help to improve the understanding of the fate of applied P in Vertosols. This will be critical for future development of sustainable P fertilizer management strategies

Factors influencing referrals for ultrasound-diagnosed complications during prenatal care in five low and middle income countries

BACKGROUND: Ultrasound during antenatal care (ANC) is proposed as a strategy for increasing hospital deliveries for complicated pregnancies and improving maternal, fetal, and neonatal outcomes. The First Look study was a cluster-randomized trial conducted in the Democratic Republic of Congo, Guatemala, Kenya, Pakistan and Zambia to evaluate the impact of ANC-ultrasound on these outcomes. An additional survey was conducted to identify factors influencing women with complicated pregnancies to attend referrals for additional care. METHODS: Women who received referral due to ANC ultrasound findings participated in structured interviews to characterize their experiences. Cochran-Mantel-Haenszel statistics were used to examine differences between women who attended the referral and women who did not. Sonographers\u27 exam findings were compared to referred women\u27s recall. RESULTS: Among 700 referred women, 510 (71%) attended the referral. Among referred women, 97% received a referral card to present at the hospital, 91% were told where to go in the hospital, and 64% were told that the hospital was expecting them. The referred women who were told who to see at the hospital (88% vs 66%), where to go (94% vs 82%), or what should happen, were more likely to attend their referral (68% vs 56%). Barriers to attending referrals were cost, transportation, and distance. Barriers after reaching the hospital were substantial. These included not connecting with an appropriate provider, not knowing where to go, and being told to return later. These barriers at the hospital often led to an unsuccessful referral. CONCLUSIONS: Our study found that ultrasound screening at ANC alone does not adequately address barriers to referrals. Better communication between the sonographer and the patient increases the likelihood of a completed referral. These types of communication include describing the ultrasound findings, including the reason for the referral, to the mother and staff; providing a referral card; describing where to go in the hospital; and explaining the procedures at the hospital. Thus, there are three levels of communication that need to be addressed to increase completion of appropriate referrals-communication between the sonographer and the woman, the sonographer and the clinic staff, and the sonographer and the hospital