Forage yield, water- and solar radiation-productivities of perennial pastures and annual crops sequences in the south-eastern Pampas of Argentina

OJEDA, J.J.; CAVIGLIA, O.P.; AGNUSDEI, M.G.; ERRECART, P.M.

FIELD CROPS RESEARCH

ELSEVIER SCIENCE BV

Año: 2018 vol. 221 p. 19 - 31

0378-4290

Livestock production systems of Argentina showan ongoing process of change in the composition of their forage base, with agradual increase in the proportion of their area assigned to forage cropsequences (FCS) -in particular that involving successive winterand summer annual forage crops?, at the expense of the area assigned toperennial pastures (PP). However, there are several concerns regarding the efficient use of availableenvironmental resources due to differences in the extent of the establishmentperiods and due to the occurrence of fallow periods in FCS, as well asregarding the species involved in these systems. Therefore, the main objectiveof this study was to evaluate the water (WP) and solar radiation productivity(RP) of PP [pure stands of alfalfa (Medicago sativa L.), fertilized and unfertilizedstands of tall fescue (Festuca arundinacea Schreb.), and fertilizedand unfertilized mixed stands of alfalfa/tall fescue] and FCS [including asummer alternative and oats (Avena sativa L.); the summer alternativewas either maize (Zea mays L.) or intercropped maize/soybean (Glycine max L.)] through the analysisof their components, i.e. water (WC) and radiation capture (RC), and theirwater (WUE) and radiation use efficiency (RUE). Resource capture (WC and RC) wasdefined as the ratio betweencaptured (evapotranspiration and intercepted solar radiation) and annualavailable resource (rainfall and incident solar radiation). Resource use efficiency (WUE and RUE) wascomputed as the dry matter (DM) yield per unit of captured resource. A field experiment wasconducted during two consecutive years under rainfed conditions and undernon-limiting nitrogen availability in the south-eastern Pampas of Argentina.Perennial pastures were evaluated during both their initial establishment year(Y1) and when already fully established (Y2). Annual-based forage DM yieldranged between 13.0 and 32.4 Mg ha-1 inY1 and between 5.1 and 23.5 Mg ha-1 inY2. Differences in resource capturebetween PP and FCS were directly associated with the crop establishment andfallow periods depending on the nature of the considered resource. The highestWP (2.75?3.64 g DM m-2 mm-1)and RP (0.93?1.42 g DM MJ-1) were reached by FCS, which did not differ (P > 0.05) from thatof fully established fertilized PP. Our results demonstrate that resourceproductivity in FCS is not necessarily higher than for PP, once PP are fullyestablished.