Effects of fertiliser application on nutrient status and organic matter content of hill soils

Abstract

Effects of two fertiliser treatments on soil characteristics were measured during 1972-87, within 10 grazed permanent-pasture "farmlets", on steep hill country in southern Hawke's Bay, New Zealand. The low fertiliser (LF) treatment received 125 kg ha-1 superphosphate p.a., and the high fertiliser (HF) an average 625 kg ha-1 p.a. for 5 years then 375 kg ha-1 p.a. subsequently. Ground limestone was applied to HF in 1975 and 1979. Grazing pressure was the same across treatments. Soil fertility decreased with increasing slope of measurement site, and aspect had a less marked effect. Phosphorus initially accumulated mainly in inorganic forms, with organic P accumulating at a slower rate similar to that for organic S. Olsen P status reflected P application regime, although the responsiveness was lower than anticipated. Soil pH in the non-limed LF treatment increased slightly over time, probably as a consequence of the decline in soil organic C. Soil total N (0-75 mm depth) A99035

Effect of nitrogen fertilizer on nitrogen pools and soil communities under grazed pastures

“…Further, at the time of commencement of the HF and LF treatments over 1972Á76 (i.e. when the land was first subjected to different management), there were no distinguishable differences between areas in either annual herbage yields (Lambert et al 1983) or soil chemical properties (Lambert et al 2000). This strongly suggests that any differences currently present are a consequence of the different fertilizer treatments and sheep stock densities over the previous 30 years, and not of any major initial difference between the two farmlets.…”

“…The topsoils have a silt loam texture. The following properties have been previously described: nutrient transfer, S and N leaching (see Parfitt et al 2010), carbon (C) inputs, soil organic matter (Lambert et al 2000), microfauna (Parfitt et al 2005) and earthworms and microarthropods (Schon et al 2008). The pH values were in the range 5.3Á5.6 at both sites, and the Olsen P values were 6Á8 mg kg (1 at LF, and 48Á53 mg kg (1 at HF (Parfitt et al 2009).…”

Simple models of carbon and nitrogen cycling in New Zealand hill country pastures: exploring impacts of intensification on soil C and N pools

“…It is interesting to estimate how much the values for R s set in our simple C model would need to decrease to achieve the annual gain in soil C measured by Schipper et al (2010), and likewise to calculate the decrease in R S needed to attain the decrease in soil C measured by Lambert et al (2000). For the base scenario, the weighted average value for R s (calculated by assuming soil C on each slope category had reached equilibrium) in the notional 1 ha paddock was 9125 kg C ha (1 yr (1 for the summer moist site and 4237 kg C ha (1 yr (1 for the summer dry site (Table 2).…”

“…For the base scenario, the weighted average value for R s (calculated by assuming soil C on each slope category had reached equilibrium) in the notional 1 ha paddock was 9125 kg C ha (1 yr (1 for the summer moist site and 4237 kg C ha (1 yr (1 for the summer dry site (Table 2). Using the work of Lambert et al (2000), where 200 kg C ha…”

“…These factors include the C/N ratio of organic residues and environmental conditions. reported that many topsoils in the hill country of the lower North Island contain very large quantities of nitrogen, rendered largely unavailable by the relatively wide C/N ratio (12Á19 depending on the micro-climate (Ledgard et al 1982(Ledgard et al , 1987Lambert et al 2000)) of the soil organic matter present. Sakadevan et al (1993a) estimated that 119 and 250 kg N ha…”