Participants Marrack Goulding

Goulding, Marrack

doi:10.1017/s0272503700065551

Cited by 2 publications

(3 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Cropping system N cycling S uptake P uptake BCs uptake Net H production Anthropogenic acidification of Chinese agricultural soils will be difficult to correct as long as excessive levels of N fertilization continue. Goulding and Annis (28) found that each 50 kg ha −1 of added ammonium-N generates ~4 kmol H + ha −1 year −1 and requires ~500 kg CaCO 3 ha −1 year −1 to neutralize in their field conditions. Similar theoretical calculations show that each kg of applied NH 4 -N leached as NO 3 -N demands 7.2 kg of CaCO 3 to neutralize the acidity generated (29,30).…”

Section: Soil Group 1980s 2000smentioning

confidence: 99%

Significant Acidification in Major Chinese Croplands

Guo

Liu

Zhang

et al. 2010

Science

3,066

1,448

View full text Add to dashboard Cite

Soil acidification is a major problem in soils of intensive Chinese agricultural systems. We used two nationwide surveys, paired comparisons in numerous individual sites, and several long-term monitoring-field data sets to evaluate changes in soil acidity. Soil pH declined significantly (P < 0.001) from the 1980s to the 2000s in the major Chinese crop-production areas. Processes related to nitrogen cycling released 20 to 221 kilomoles of hydrogen ion (H+) per hectare per year, and base cations uptake contributed a further 15 to 20 kilomoles of H+ per hectare per year to soil acidification in four widespread cropping systems. In comparison, acid deposition (0.4 to 2.0 kilomoles of H+ per hectare per year) made a small contribution to the acidification of agricultural soils across China.

show abstract

Section: Soil Group 1980s 2000smentioning

confidence: 99%

Significant Acidification in Major Chinese Croplands

Guo

Liu

Zhang

et al. 2010

Science

3,066

1,448

View full text Add to dashboard Cite

show abstract

“…We expect violence. 48 That the UN officials simply could not believe that almost a year into the ''unofficial'' cease-fire Nujoma would embark on such a reckless undertaking is understandable. Hindsight now points to a pattern of clues, but at the time the only discernible pattern was Nujoma's outbursts.…”

Section: Missed Opportunity For Early Warningmentioning

confidence: 99%

“…And even then it agreed to only 28 UNTAG observers to ''monitor the [Angolan] monitors.'' 51 This was a point of dispute for Pik Botha and other South African officials who knew that the Angolan government forces were lax in their duties and partial to SWAPO. Had UNTAG gained access to the bases in Angola in April while Botha was claiming a build-up of SWAPO forces along the border, the United Nations might have had important counter-information on the number of guerrillas in Angola and their motivations.…”

Section: Untag's Limitationsmentioning

confidence: 99%