M. G. Lambert

Influence of fertiliser and grazing management on North Island moist hill country

Abstract A grazing trial was conducted on 99 ha of moist, low-fertility hill country near Woodville, New Zealand, during 1975-1981. Treatments were: low fertiliser (125 kg/ha/a superphosphate (9% P, 10% S)) and high fertiliser (average 630 kg/ha/a superphosphate, plus lime) application rates; and 3 grazing managements — rotational grazing by sheep and by cattle, and set stocking by sheep. Some replication was included in the design, 10 self-contained farmlets being used. Over a 6-year period stocking rate was increased from 6.5 to 12.0 and from 8.8 to 16.1 s.u./ha on low and high fertiliser farmlets respectively. Over this period, and also in the 3 previous years, herbage accumulation was measured, using grazing exclosures and a trim technique. November-April rainfall had a large effect on herbage accumulation rate (HAR) causing year-to-year variation of 23% about mean annual herbage accumulation. The high fertiliser treatment grew 9% more herbage than low fertiliser in the first year after differential a...

Influence of fertiliser and grazing management on North Island moist hill country 2. Pasture botanical composition

Abstract A grazing trial was conducted on 99 ha of steep, low fertility hill country in southern Hawkes Bay, during 1975–81. There were 2 fertiliser treatments: low (LF) and high (HF) superphosphate application (plus lime on HF), and 3 grazing managements — rotational grazing by sheep (RGS) or cattle (RGC), and set stocking by sheep (SSS). As part of a larger measurement programme, botanical composition of pastures was monitored over the 6-year period. HF pastures had a greater content of ryegrass (Lolium perenne L.) and legumes than LF pastures, and a smaller content of low fertility tolerant (LFT) grasses (e.g., browntop, Agrostis capillaris L.; sweet vernal, Anthoxanthum odoratum L.) and weed species. Ryegrass content of pasture under the 3 managements was in the order RGC > RGS > SSS. RGC pastures had a smaller content of LFT grasses, and a greater content of legumes than sheep-grazed pastures. SSS pastures were more weedy than those rotationally grazed. Slope and aspect of measurement site also infl...

A nutrient-transfer model to explain the fate of phosphorus and sulphur in a Grazed Hill-Country pasture

Abstract A nutrient-transfer model was developed using a mass balance approach to explain the variations in the amounts of soil phosphorus (P) and sulphur (S) found across a range of slopes and aspects in four 10-ha farmlets located in summer-moist hill-country pastures in the southern North Island of New Zealand. The farmlets were continuously grazed by sheep for a period of 12 years, during which time they received a total of 115, 187, 387, 603 and 126, 201, 405, 630 kg ha −1 of P and S, respectively, as single superphosphate (SSP). The model takes account of the effect of topography and local climate on stock behaviour, herbage accumulation and its nutrient content, pasture utilization and the uneven nutrient return through excreta. The developed P model was reliable. The predictions of the transfer model explained 95% of variation in soil P amounts (0–150 mm depth) between farmlets ( n =4), 89% of variation between slope units ( n =12) and 79% between slope-aspect units ( n =36) across all farmlets. When S input parameters were substituted for P parameters, the model was unable to predict the measured soil S levels in any of the four farmlets. Unlike P, S is subject to losses by leaching from these soils. The differences between predicted and measured soil S amounts were used to estimate S leaching losses and pinpoint areas from where they occurred. The concept of modelling the fate of P in P and S fertilized systems and then using the calculated nutrient-transfer functions of the model to evaluate the fate of S provides invaluable information for developing strategies for improving the efficiency of S fertilizer use.

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 Hawkes 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) remained constant in LF, but increased by 19 kg ha‐1 yr‐1 in HF soils. Soil carbon decreased in LF and HF by 200 kg C ha‐1 yr‐1 This suggests that soil organic matter may be decreasing in some New Zealand pastoral environments.

Short‐term ingestive behaviour of sheep and goats grazing grasses and legumes

Bite weight, bite rate, and bite dimensions (depth, area, and volume) were compared among six sheep and six goats individually confined indoors in metabolism crates, grazing monoculture turves (41 × 27 cm) of five grasses and four legumes at the vegetative and reproductive stages of growth. Each sampling period was restricted to 12–17 bites. Leguminous swards resulted in a greater overall fresh bite weight (1253 versus 994 mg fresh matter (FM), SE = 41, P < 0.001) despite a shallower bite depth (6.1 versus 22.1 cm, SE = 0.6, P < 0.001) compared with gramineous swards. Animals also obtained a faster bite rate on legumes than on grasses (28 versus 24 bites/min, SE = 0.8, P < 0.001). The taller reproductive swards led to greater bite weight (1297 versus 920 mg FM, SE = 37, P < 0.001), but lower bite rate than vegetative swards (18 versus 33 bites/min, SE = 1; P < 0.001). Consequently, short‐term intake rate did not change significantly with increased maturity (6.1 versus 5.7 g DM/min, SE = 0.2). Mea...

Influence of fertiliser and grazing management on North Island moist hill country 4. Pasture species abundance

Abstract A grazing trial was conducted on steep, moist, low fertility hill country in the southern Hawkes Bay during 1975–81. There were 2 fertiliser treatments: low (LF) and high (HF) superphosphate application (plus lime on HF), and 3 grazing managements — rotational grazing by sheep (RGS) or cattle (RGC), and set stocking by sheep (SSS). Annual measurements of pasture species abundance (plant unit density and size) were made in each year during 1976–81. Density of plant units was greater in HF than LF (27.8 cf. 25.3 × 103/m2) pastures and, for the 3 different grazing managements, SSS > RGS > RGC (30.1, 25.2, and 17.1 × 103/m2 respectively). In addition, plant density decreased with increasing slope of measurement site, and was influenced by aspect. In most instances, lower plant unit density was compensated for by increases in plant unit size, in accordance with the ‘3/2 thinning law’. This did not occur under RGC because of severe treading damage, and the depression in herbage accumulation rate in th...

Influence of fertiliser and grazing management on North Island moist hill country 3. Performance of introduced and resident legumes

Abstract A grazing trial was conducted on 99 ha of steep, low fertility hill country in southern Hawkes Bay, during 1975–81. There were 2 fertiliser treatments: low (LF) and high (HF) superphosphate application (plus lime on HF), and 3 grazing managements — rotational grazing by sheep (RGS) or cattle (RGC), and set stocking by sheep (SSS). A white clover (Trifolium repens L.) similar to Kent wild white, and annual suckling clover (T. dubium Sibth.) were already present in the pastures in small amounts. ‘Grasslands Huia’ white clover, ‘Grasslands Turoa’ red clover (T. pratense L.), ‘Grasslands Maku’ lotus (Lotus pedunculatus Cav.), and Woogenellup subterranean clover (T. subterraneum L.) were oversown into the pasture in 1974. Huia, Turoa, and Grasslands 4703 lotus were oversown again in 1977. Woogenellup subterranean clover was found to be unsuited to the environment. Lotus plants established, but contributed little to total herbage accumulation. Red clover was most important in RGC pastures. Its contrib...

Inheritance of phosphorus response in white clover (Trifolium repens L.)

Genotypes of white clover that exhibited divergent responses to P were identified in a glasshouse pot trial. Six high P-responding genotypes were selected from previously identified high P-responding cultivars and 5 low P-responding genotypes were selected from previously identified low P-responding cultivars. These were crossed in a full diallel design without selfing and reciprocals were kept separate. The P-response of progeny lines was compared with parents. High P-response was dominant over low P-response with progeny from crosses between high and low P-response genotypes being similar to the high P-response parent. Reciprocal effects were not significant. The general combining abilities of high P-response genotypes were generally greater than that of the low P-response genotypes, although there were significant specific combining abilities. Narrow sense heritabilities for P response were moderate, 0.46 based on the linear coefficient and 0.33 based on the quadratic coefficient of the fitted response curves.

Introduction, production, and persistence of five grass species in dry hill country: 5. Central Wairarapa, North Island, New Zealand

A trial was conducted on a seasonally dry slope near Taupo as part of a national series investigating the persistence and productivity in dry hill country of five grass species established from oversowing under contrasting nitrogen (N) and summer grazing regimes. The average annual total herbage accumulation (HA) (1983–87) was greatest from phalaris (Phalaris aquatica L. ‘Grasslands Maru’) swards (12100 kg DM/ha, 65% Maru); followed by a species mixture (11700 kg DM/ha); tall fescue (Festuca arundinacea Schreb. ‘Grasslands Roa’) (11700 kg DM/ha, 47% Roa); prairie grass (Bromus willdenowii Kunth ‘Grasslands Matua’) (11300 kg DM/ha, 25% Matua); cocksfoot (Dactylis glomerata L. ‘Grasslands Wana’) (11100 kg DM/ha, 56% cocksfoot); resident swards (10640 kg DM/ha); and was least from ryegrass (Lolium perenne L. ‘Grasslands Nui’) (10200 kg DM/ha, 73% ryegrass). The average response from a split application of 50 kg N/ha in each of autumn and spring, was a 14% increase in annual HA. Summer grazing treatm...

Response to phosphorus of a world collection of white clover cultivars

White clover (Trifolium repens L.) is the predominant legume of temperate pastures. Nitrogen (N) fixed by white clover is essential for maintaining the production of grasses in agricultural systems where N fertilisers are not used. However, white clover is a poor competitor for soil phosphate (P). This is of particular significance when many soils in New Zealand and throughout the world are P deficient. The increasing cost of manufacture and application of P fertilisers has stimulated a breeding programme to develop a white clover with improved P nutrition.