I. Zanichelli

L. Bechini

M. Penati

AIR Universita degli studi di Milano

AGROECOLOGICAL INDICATORS OF CROPPING SYSTEMS: THE PHOSPHORUS INDICATOR IN THE SUD MILANO AGRICULTURAL PARK (NORTHERN ITALY)  L. Bechini1, M. Penati2, I. Zanichelli2  1DiProVe, University of Milano, Via Celoria 2, 20133 Milano, Italy, luca.bechini@unimi.it 2Parco Agricolo Sud Milano (PASM), Via Pancrazi 10, 20145 Milano, Italy  Introduction Agroecological indicators (OECD, 2001) are useful to integrate data about cropping and farming systems and to draw conclusions about their sustainability. One important aspect of sustainability is the management of nutrients; for this reason we calculated nutrient budgets (Bechini et al., 2004) for the farms of the regional agricultural metropolitan Park "Parco Agricolo Sud Milano" (PASM). However, nutrient budgets do not consider the availability to the crop of nutrients contained in the soil. To overcome this limitation, in this paper we describe the application of a phosphorus (P) indicator (Bockstaller and Girardin, 2000) at the cropping systems of PASM.  Materials and methods After simplifying it, we calculated the P indicator proposed by Bockstaller and Girardin (2000) as: Ip=10+max(min(Psoil, Pres), -10). Psoil considers soil P depletion generated by insufficient P fertilizer application: if Pina<PR, then Psoil=(Pina-PR)/30, where Pina=P applied which is available to crop in that soil (kg P2O5 ha-1); PR=crop P requirement (kg P2O5 ha-1), calculated on the basis of available P in soil (Pavail, ppm) and expected crop P uptake (Puptk, kg P2O5 ha-1). PR can be zero if Pavail is at least sufficient. On the other side, Pres considers excess fertilizations, which would consume non-renewable resources (and accumulate P in soil) when organic and/or inorganic P are applied to soils with sufficient Pavail: if Pin>PR then Pres=-(Pin-PR)/30, where Pin=P applied to the soil (kg P2O5 ha-1). Ip=10 identifies the systems where P fertilization is correct; lower values indicate excess or deficit fertilization (e.g. Ip=5 indicates an excess or deficit fertilization of 150 kg P2O5 ha-1). The indicator was calculated for the cropping systems described in the SITPAS database, which includes detailed information about crop management; crop data are georeferenced through the cadastral map. One or more cadastral parcels may be cultivated with one rotation, which in turn is composed of one or more crops. Therefore, by using the rotation entity-set, it is possible to georeference all the data related to a particular crop. To calculate the indicator: i) we derived Pina, Pin and Puptk from the database, with the same methodology used for the nutrient budgets (Bechini et al., 2004); ii) we derived Pavail from the SITPAS soil fertility information system, which includes estimates of soil variables obtained with ordinary kriging on a 100 m by 100 m grid (De Ferrari et al., 2002); iii) by overlaying the cadastral map and the grid of soil fertility, we assigned P management information (Pin, Pina and Puptk) to each grid point; iv) we calculated the indicator for each grid point and for each crop of the rotation linked to that grid point; v) we finally averaged the results (weighing by the area occupied by each crop), for each crop type (to derive table results) and for each grid point (to derive the map). The calculations were made on 576 farms, 965 rotations, 2349 crops, 54 crop types, covering 24,516 ha (69% of PASM agricultural area).  Results and discussion Overall (Table 1), the average value (6.6) is not at all encouraging, when one reminds that 30 kg P2O5 ha-1 (excess or deficit) correspond to 1 indicator unit. Its value is mainly determined by Pres, which for 96% of the area is lower than Psoil (for 4% of the area Psoil=Pres=0, i.e. Ip=10; only on 2.6 ha Psoil is lower than Pres). This indicates a substantial excess of P fertilizers applied. For the entire Park, 30% of the area has Ip<5.8, 50% is below 7.0, and 70% is below 8.5. For rape, set-aside and soybean, excess P fertilization is not very relevant. For most crop types, Ip is still above the Park average, but with relevant excess fertilizations in the range 40-90 kg P2O5 ha-1. The lowest average, indicating a large, useless P consumption, was obtained for maize, for which the average excess is 150 kg P2O5 ha-1. In general, the excess fertilization is determined by the high levels of Pavail in the soil: Pavail is so high that P fertilization would almost never be required (PR<1.3 kg P2O5 ha-1 for 99% of the area). The map (Figure 1) allows to analyse the spatial distribution of Ip and to identify the most critical situations.  Conclusions By integrating different data, we can conclude that one of the most important actions to be taken in the Park is to reduce or eliminate P applications on P-rich soils. However, because most of the data used in this study are uncertain kriged estimates, literature data or collected during interviews, we will develop methodologies to assess the uncertainty of the indicator.  References Bechini L. et al., 2004. Agroecological indicators of cropping systems... These proceedings. Bockstaller C., Girardin P., 2000. Mode de calcul des indicateurs agro-ecologiques, INRA. De Ferrari G. et al., 2002. Informatore Agrario, 13, 27-30. OECD, 2001. Environmental Indicators for Agriculture. Vol 3. Paris, France.  Acknowledgments Prof. T. Maggiore coordinated the SITPAS project, which was financed by Provincia di Milano, Regione Lombardia, CCIAA. Prof. S. Bocchi and Dr. R. Confalonieri started this work with us. Crop Area (ha) avg. s.d. 5° 95° avg. s.d. 5° 95°Maize 9394 5.0 2.6 0.0 8.6 -5.9 5.1 -14.7 -1.4Rice 5966 7.0 1.7 3.3 9.2 -3.0 1.7 -6.7 -0.8Permanent meadows 2799 7.2 2.8 1.2 10.0 -2.9 3.1 -8.8 0.0Soybean 1650 9.0 1.0 7.1 9.9 -1.0 1.0 -2.9 -0.1Barley 1006 8.3 2.1 3.4 9.9 -1.9 3.3 -6.6 -0.1Italian ryegrass 927 7.7 2.5 2.1 9.9 -2.4 2.8 -7.9 -0.1Winter wheat 691 8.2 1.8 5.1 9.8 -2.0 3.0 -4.9 -0.2Rotated meadows 416 7.4 1.8 3.8 10.0 -2.6 1.8 -6.2 0.0Rape 386 9.3 0.3 8.8 9.7 -0.7 0.3 -1.2 -0.3Alfalfa 266 8.6 2.3 3.4 10.0 -1.4 2.4 -6.6 0.0Set-aside 139 9.3 0.5 8.2 9.7 -0.7 0.5 -1.8 -0.3Other crops 877 7.7 2.6 2.6 10.0 -2.6 3.8 -7.4 0.0All Park 24516 6.6 2.7 0.2 9.9 -3.8 4.1 -9.9 -0.1Ip PresTable 1 – Phosphorus indicator (Ip) and contribution to Ip of excess fertilisations (Pres) for the most important crop types Avg. = average; sd = standard deviation; 5° and 95° = 5th and 95th percentiles Figure 1 - Map of the phosphorus indicator for the entire Park  

Agroecological indicators of cropping systems: the phosphorus indicator in the Sud Milano agricultural park (northern Italy)

https://air.unimi.it/retrieve/handle/2434/13038/87609/phosphorus_esa_2004.pdf

Agroecological indicators of cropping systems: the phosphorus indicator in the Sud Milano agricultural park (northern Italy)

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