Perhaps genetic engineering could help to increase the efficiency with which crops absorb nitrate from soil (5 January, p 28). However, the claim by Arcadia Biosciences that this will substantially cut agricultural emissions of the greenhouse gas nitrous oxide appears Utopian rather than Arcadian. (Letters)

"We apologise for recent price increases," reads the sign over the bread counter, "but they are due to global factors beyond our control." This is not a Third World food stall but an upscale supermarket in Brussels, capital of the European Union, whose farming system was once notorious for the mountains of surplus grain it produced. Those mountains are now gone. The world is down to its lowest grain stocks for decades, and food prices are up around the world.

Farming contributes more to global warming than all the world's cars, trains, ships and planes put together. And the single biggest problem with farming is not carbon but nitrogen. From the maize fields of Kansas to the emerald rice paddies of China, today's bountiful harvests depend on generous applications of nitrogen fertiliser. Although only a tiny proportion escapes into the atmosphere as nitrous oxide, it is an extremely potent greenhouse gas. It's a vexing problem, but Eric Rey believes he has some of the answers, in the form of crops genetically modified to require less fertiliser.

More than a decade after the first commercial plantings of genetically modified crops, the same old disagreement rumbles on. On one side stand agribiotech companies, arguing that crops engineered to produce insecticidal proteins or resist herbicides boost yields in an environmentally friendly way. Opposing them are advocacy groups who charge that these crops, or the farming practices they encourage, threaten biodiversity. (Editorial)

With the aim to study the comparative effects of vermicompost, farm yard manure, biofertilizer and chemical fertilizers on growth, yield and quality of food product, the most common vegetable crop - Lady's Finger was selected and the impact of these four supplements on shoot length, fruits, plant and protein content of the fruit was studied by growing this crop in the botanical garden of S.B., P.G. College, Baragaon Campus, in the year 2005 and 2006.

In ancient India, agriculturists were quite aware of the relation between soil properties and crop production. Several systems of soil classification were in vogue. Ancient Indian scriptures contain elaborate injunctions regarding the use of various kinds of manures for crop production.