Affamati di Scienza

AMSTERDAM – Sul delta del Mekong, gli agricoltori ottengono 6-7 tonnellate di riso per ettaro nelle stagioni secche e 4-5 tonnellate per ettaro nelle stagioni umide, utilizzando varietà di riso a maturazione rapida che permettono fino a tre raccolti consecutivi all’anno. Al contrario, i coltivatori di riso dell’Africa occidentale raccolgono all’anno solo 1,5 tonnellate per ettaro del tradizionale riso d’altura, mentre degli altri cereali non se ne producono più di una tonnellata - una cifra paragonabile ai rendimenti dell’Europa medievale.

Tali disparità hanno motivo di esistere. In effetti, la proliferazione di tecnologie agricole - dai macchinari più efficienti a varietà di colture ad alto rendimento o più resistenti – possiede le potenzialità per una riduzione notevole del divario di produttività, anche se rimangono le differenze tra i climi e tra i produttori.

Ad esempio, in Africa, una nuova varietà di riso da produrre in zone aride, il Nerica, triplica i rendimenti annuali. Allo stesso modo, nel corso degli ultimi quarant’anni, il miglioramento dei metodi di allevamento, i mangimi di qualità superiore, e le migliori cure veterinarie hanno più che raddoppiato la produzione media di latte in tutto il mondo. Tuttavia, le discrepanze regionali restano enormi: le mucche nei Paesi Bassi sono in grado di produrre circa 9 mila litri di latte all’anno, mentre ai tropici gli allevamenti di Zebù ne producono solo circa 300 litri.

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