Aspects of management options for pasture-based dairy production stocked at two cows per hectare

End of project reportWhite clover in association with Rhizobium bacteria have the capacity to fix or convent atmospheric N into plant available N. This can make a considerable contribution to sward productivity. One of the objectives of this experiment was to determine the upper carrying capacity of grass-white clover swards receiving 90 kg fertilizer N/ha. A second objective was to examine the impact of grass-clover swards on mineral-N in the soil and losses of nitrate-N from soil to drainage water during the winter. This experiment was conducted at Solohead Research Farm. There were three treatments: (i) A grass-only treatment (FN) stocked at 2.0 cows per ha in 2003 and 2.2 cows per ha during 2004, 2005 and 2006. This treatment received an average of 226 kg per ha of fertilizer N per year during these years. (ii) A grass-clover treatment (WC) stocked at the same rates as FN and received an average of 90 kg per ha of fertilizer N per year during the experiment. (iii) A grass-only treatment (CC) that was gradually converted over to grass-clover during the experiment and stocked at 2.0 cows per ha throughout the experiment. Fertilizer N input was gradually lowered from 150 kg per ha in 2003 to a target of 90 kg per ha in 2005 and 2006

The development of systems of milk production and grazing management based on low stocking rates and very low artificial nitrogen inputs.

End of Project ReportThere is increasing pressure on to reduce nitrogen (N) inputs to agricultural production systems within the European Union. This three-year experiment examined the impact of lowering N-input/ha on milk output, carrying capacity and N losses. In Ireland, a dairy cow is classified as excreting 85 kg organic N per year. There were four treatments involving annual stocking rates and fertilizer N inputs as follows: (1) 2.5 cows/ha & 350 kg/ha (Intensive), (2) 2.5 cows/ha & 250 kg/ha (Moderate), (3) 2.1 cows/ha & 175 kg/ha (Extensive) and (4) 1.75 cows/ha & 80 kg/ha (Minimal). Swards were initially composed predominantly of perennial ryegrass and contained white clover. The primary aim was to supply sufficient pasture to meet the feed requirements of the lactating cows during the main grazing season. Subject to meeting this requirement the objective was to produce enough grass to meet winter-feed requirements as grass-silage. Production of grasssilage was indicative of carrying capacity. There were 18 cows per treatment each year. Concentrates fed were 595 kg/cow/year. There were no significant differences in yields (mean ± SEM kg/cow/year) of solids-corrected milk (6210 ± 97), fat (263 ± 4.4), protein (225 ± 3.3) and lactose (301 ± 5.2) between treatments combined over years. Silage production was sufficient to meet winter-feed requirements (i.e. 1.40 t DM/cow) on all treatments except Moderate, which was 0.87 of requirement. Measurement of soil mineral N concentrations indicated largest losses from Intensive during the winter. However, measurement of nitrate N in drainage water during the winter indicated low concentrations (mg/litre) from all treatments; 2.4 from Intensive, 2.0 from Mininal, 0.9 from Moderate and 0.9 from Extensive. The comparably high mean concentrations associated with Minimal were attributed to the high proportion of white clover in these swards and the breakdown of clover stolon releasing mineral N into the soil during the winter months. The main findings were: (1) No difference in milk output per cow even under low fertilizer N inputs (2) A relationship between requirement for fertiliser N and stocking rate along the line: Fertilizer N req. = (SR x 300) – (300 + background-N) Where SR is stocking rate in cows per ha and background N is the release of N from net mineralization of soil organic matter N. The average value for background-N is around 130 kg/ha. (3) Very high levels of productivity from grass + white clover swards receiving 80 kg N/ha/year with around 80% of the carrying capacity of the Intensive treatment. (4) Very low losses of nitrate-N in drainage water under organic N loads of up to 300 kg/ha. Losses of nitrate-N in drainage water accounted for less than 5% of N losses in the experiment except on the clover-system. It is likely that denitrification and losses of di-nitrogen (N2) and nitrous oxide (N2O) gasses were the main pathways for loss. This is consistent with the heavy wet imperfectly drained soils, high rainfall, intermittent soil saturation and the mild conditions experienced at Solohead

Aspects of management options for pasture-based dairy production stocked at two cows per hectare

End of project reportWhite clover in association with Rhizobium bacteria have the capacity to fix or convent atmospheric N into plant available N. This can make a considerable contribution to sward productivity. One of the objectives of this experiment was to determine the upper carrying capacity of grass-white clover swards receiving 90 kg fertilizer N/ha. A second objective was to examine the impact of grass-clover swards on mineral-N in the soil and losses of nitrate-N from soil to drainage water during the winter. This experiment was conducted at Solohead Research Farm. There were three treatments: (i) A grass-only treatment (FN) stocked at 2.0 cows per ha in 2003 and 2.2 cows per ha during 2004, 2005 and 2006. This treatment received an average of 226 kg per ha of fertilizer N per year during these years. (ii) A grass-clover treatment (WC) stocked at the same rates as FN and received an average of 90 kg per ha of fertilizer N per year during the experiment. (iii) A grass-only treatment (CC) that was gradually converted over to grass-clover during the experiment and stocked at 2.0 cows per ha throughout the experiment. Fertilizer N input was gradually lowered from 150 kg per ha in 2003 to a target of 90 kg per ha in 2005 and 2006

REMAINS OF THE SOCIAL DESIRING THE POSTAPARTHEID

REMAINS OF THE SOCIALREMAINS OF THE SOCIAL progress in his ‘Theses on the Philosophy of History’. Indeed, what is explored here, in various ways, is the notion that the very question of loss, as Zita Nunes has argued, might be read not only as constitutive of, or constituted by, the social – the social produced through loss, the grave as its first commemorative sign, or the social apportioning life and death and designating its grievability – but rather as a masking of that which enables the constitution of the social: the remainder, which we propose against conceptions of mourning and its failures, melancholia and nostalgia, which one finds more frequently in studies on the social. There is an echo here, as we discuss in the introductory chapter, of Fanon’s critique in Black Skin, White Masks of the social as it is constituted through the concept of Man, an echo that brings with it not only the urgent task of posing questions of racial formations, but also a need to turn attentively to modes of narration that enable an encounter with these remainders as resistant: to read this resistance back into the social as a demand that orders a future which is, as Fanon puts it in his opening lines, always too soon and too late, out of time. Such a demand is what threads the ethical weight that the chapters in this volume bring to the question of the social.WITS University PressLP201