Regional Soil Nutrient Balances for Cropland in 1920s Catalonia, Spain

Abstract

Understanding the replacement of soil nutrients removed by harvests makes it possible to understand the influence of humans on long-term soil fertility. This article calculates nitrogen, phosphorous, and potassium balances for cropland in 1920 for three agroecoregions distinguished by particular historical settlement patterns, land use, geography, and climatic characteristics in Catalonia, Spain. The analysis assesses and compares the regional potential for farmers to have returned the nutrients extracted from croplands at a time of transition, when only a few synthetic fertilizers were yet available. From sustainability science, the article borrows a methodology to reconstruct soil nutrient balances in historical agroecosystems from available regional historical sources. The soil balances indicate that nutrient extractions were balanced with the additions in Catalonia's wetter Pyrenees and eastern regions, but were in deficit in the arid western regions, where less livestock manure was available. In Barcelona province, farmers made considerable use of synthetic fertilizers already in 1920. Such fertilizers were mainly intended to supplement phosphorus in the eastern region, suggesting that they played an important role there too, where there was not enough manure.