Improving resource productivity at a crop sequence level
The challenge to increase agricultural production with a minimum environmental impact requires to reach themaximum effiency in the capture and use of resources such as photosynthetically active radiation (PAR), water,and nitrogen (N). Such requisites are encompassed in the ecological intensifiation (EI) concept. The aims of this work were to evaluate at a crop sequence level: i) crops yields, ii) water and radiation productivity and itscomponents, i.e. resource capture and resource use effiency, and iii) partial factor productivity of applied N(PFPN), partial nutrient balance for N (PNB), N uptake and N utilization effiency of a two-year, three-cropsequence (wheat [Triticum aestivum L.]/soybean [Glycine max (L.) Merr.] double crop – maize [Zea mays L.])carried-out under EI principles in comparison with the same crop sequence under current farmer practices (FP) intwo contrasting locations of the Argentinean Pampas, i.e. Paraná (-31°50′; -60°31′) at the northern Pampas andBalcarce (-37°45′, -58°18′) at the southern Pampas. Experiments were carried-out during four consecutive years,covering two complete cycles of the crop sequence. For the accumulated grain production of the crop sequence, EI management outyielded FP from 13 to 42%, depending on environmental conditions. Maize yield accounted formost of the variation (41–64%) of the accumulated grain yield of crop sequence, whether in EI as in FP. Averagegrain yield diffrences between EI and FP treatments were 274 g m−2 for maize, 69 g m−2 for wheat and -2 g m−2for soybean. Water and radiation productivities of the sequence were higher in EI than in FP (26% for water and17% for radiation; P < 0.0001), mainly because of increases in resource use effiencies. EI reduced partial factorproductivity of applied N, but improved partial nutrient balance for N as compared with FP. These reductions inpartial factor productivity of applied N were less than proportional than the increases in N rate. Moreover, in spiteof the higher N rate in EI respect to FP, N utilization effiency (NutE), i.e. grain per unit N uptake, was higher across all situations in EI. Our results showed that the challenge to obtain high grain yields by increasing N rate in amedium-input system could be achieved even with an increase in NutE. Grain yields improvements, and increasesin radiation and water productivity were reached by applying a set of agronomic practices that included improvedgenetics, crop and fertilizer N management englobed under EI concept.