Nutrient uptake in tropical turfgrasses growing in winter in southern Queensland

Abstract

The effects of fertilisers on 8 tropical turfgrasses growing in 100-L bags of sand were studied over winter in Murrumba Downs, just north of Brisbane in southern Queensland (latitude 27.4°S, longitude 153.1°E). The species used were: Axonopus compressus (broad-leaf carpetgrass), Cynodon dactylon (bermudagrass ‘Winter Green’) and C. dactylon × C. transvaalensis hybrid (‘Tifgreen’), Digitaria didactyla (Queensland blue couch), Paspalum notatum (bahiagrass ‘38824’), Stenotaphrum secundatum (buffalograss ‘Palmetto’), Eremochloa ophiuroides (centipedegrass ‘Centec’) and Zoysia japonica (zoysiagrass ‘ZT-11’). Control plots were fertilised with complete fertilisers every month from May to September (72 kg N/ha, 31 kg P/ha, 84 kg K/ha, 48 kg S/ha, 30 kg Ca/ha and 7.2 kg Mg/ha), and unfertilised plots received no fertiliser. Carpetgrass and standard bermudagrass were the most sensitive species to nutrient supply, with lower shoot dry weights in the unfertilised plots (shoots mowed to thatch level) compared with the fertilised plots in June. There were lower shoot dry weights in the unfertilised plots in July for all species, except for buffalograss, centipedegrass and zoysiagrass, and lower shoot dry weights in the unfertilised plots in August for all species, except for centipedegrass. At the end of the experiment in September, unfertilised plots were 11% of the shoot dry weights of fertilised plots, with all species affected. Mean shoot nitrogen concentrations fell from 3.2 to 1.7% in the unfertilised plots from May to August, below the sufficiency range for turfgrasses (2.8–3.5%). There were also declines in P (0.45–0.36%), K (2.4–1.5%), S (0.35–0.25%), Mg (0.24–0.18%) and B (9–6 mg/kg), which were all in the sufficiency range. The shoots in the control plots took up the following levels (kg/ha.month) of nutrients: N, 10.0–27.0; P, 1.6–4.0; K, 8.2–19.8; S, 1.0–4.2; Ca, 1.1–3.3; and Mg, 0.8–2.2, compared with applications (kg/ha.month) of: N, 72; P, 31; K, 84; S, 48; Ca, 30; and Mg, 7.2, indicating a recovery of 14–38% for N, 5–13% for P, 10–24% for K, 2–9% for S, 4–11% for Ca and 11–30% for Mg. These results suggest that buffalograss, centipedegrass and zoysiagrass are less sensitive to low nutrient supply than carpetgrass, bermudagrass, blue couch and bahiagrass. Data on nutrient uptake showed that the less sensitive species required only half or less of the nitrogen required to maintain the growth of the other grasses, indicating potential savings for turf managers in fertiliser costs and the environment in terms of nutrients entering waterways.

Evidence, Regulation, and Consequences of Nitrogen-Driven Nutrient Demand by Turfgrass

“…Considerable variability in nutrient use efficiency has been observed for different turfgrass species and their cultivars [24][25][26][27], raising the specter that choice of species or cultivar can significantly alter fertilizer requirements. The assumption has been that genetics somehow gives rise to turfgrass species and cultivar differences in nutrient use efficiencies.…”

“…The data of Mehall et al [24] for 15 field grown Kentucky bluegrass cultivars similarly show that differences in cultivar growth rates accounted for 73 to 84% of the differences in tissue P and K content. Menzel and Broomhall [26], who grew eight tropical turfgrass species under different fertility regimes, observed significant differences in growth responses and nutrient uptake. Analysis of their data shows that species differences in clipping production could account for 76 to 98% of the variations in N, P, and K uptakes.…”

“…Variable nutrient demand at a fixed soil supply may account for difficulties encountered in soil test calibrations and interpretations for turfgrass [23], for reported differences in turfgrass species and cultivar nutrient requirements and nutrient use efficiencies [24][25][26], for lack of relationships between tissue cation and soil exchangeable cation concentrations [27,28], and for lack of K luxury consumption by turfgrass [29].…”

Response of tropical turfgrasses to recycled water in southern Queensland

“…The 8 tropical grass species were the same as those used by Menzel and Broomhall (2006) and included Axonopus compressus (broad-leaf carpetgrass), Cynodon dactylon and C. dactylon × C. transvaalensis hybrids (bermudagrasses 'Winter Green' and 'Tifgreen'), Digitaria didactyla (Queensland blue couch), Paspalum notatum (bahiagrass '38824'), Stenotaphrum secundatum (buffalograss 'Palmetto'), Eremochloa ophiuroides (centipedegrass 'Centec') and Zoysia japonica (zoysiagrass 'ZT-11').…”

“…The grasses were planted in October 1999 and were involved in a nutrition experiment using potable water from May to August 2001 (Menzel and Broomhall 2006). The plants were fertilised and mown to thatch level from September 2001 to April 2002, and re-randomised.…”