4.4.1.1 Distribution of arable lands among years
In figure 4.3 the distributions of arable lands are reported for each year and regime. Data is referred to each single arable land sampled by RICA database so historical aspect is not taken into account.
As shown in the above figure, this analysis considers the major part of arable land for each regime and year. Only arable lands of MIX regime, which describe farms with intermediate level of organic practices, are completely neglected. A number of arable lands neglected so little supports crop classification adopted for analysis of arable surfaces and farm structures. Indeed other crops are never relevant presence at national level.
The histogram also shows high differences in terms of arable land number among CON and ORG which could affected result comparisons.
Figure 4.3: distributions of arable lands in terms of number of arable lands. The bars are grouped in 3 regimes, on the left side MIX is reported (only for year 2007); in the middle CON and in the right side ORG is shown. Each bar is divided in 2 parts: the lower one describes arable lands considered for analysis; the upper part reports arable lands covered by other crops (MIX has only this types of arable lands).
4.4.1.2 Descriptions of farms with arable lands
The previous analysis reports 40247 selected arable lands for a total amount of 15330 farms. In this part that farms are described to individuate which ones can be analysed by historical viewpoint. The first step is to create sequence of sampled arable lands for each farm and recording wide of sample period (from 1 to 5 years).
Then farms with a sample period wider than 1 year, must be respect some constraints to not altered final results. Indeed farms with no homogeneous regime for whole period are not considered because regime transition might affected farmer crop selection. Also farms with variability of arable land surfaces among years are neglected. The reason is that these variations should affected rotational scheme identification.
The wide sample period, regime variability and arable surfaces variability are reported for each farms in figure 4.4.
The first pie chart shows that 1 farm on 3 is sampled just once. The other farms are distributed among sample period with a trend which gently decrease wih wide of sample period. However the period of 5 years records the largest number of farms among multi-year periods.
The second pie chart records high level of regime stability. More than 97% of farms reports the same regime for all sample period. This result should be affected by high presence of farms sampled one year which have forcedly a homogeneous regime. But also not considering them the farms with homogeneous regime for all sample period are more than 95%. It suggests high farm stability in terms of adopted regime.
2007 2007 2008 2009 2010 2011 2007 2008 2009 2010 2011 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 414 9861 7074 7160 7537 7458 271 241 123 225 297 RICA arable lands for MIX CON ORG regimes for years
OTHER Selected
Figure 4.4: wide of sample period, regime variability and arable surfaces variability distributions are reported in terms of farm numbers (farms with other crops are not considered.) The legends are next respective pie chart.
The third pie chart reports distribution of arable surface variability classes in terms of percentage. The arable surfaces of the same farm have been compared in all chances in terms of percentage value. The highest recorded percentage has been used to describe arable surface variability of each farm. A variability under 5% is not considered to affected in relevant way the identification of rotational schemes. The farms with higher levels of variability are neglected. They are 1 farm on 3 in general. However if only farms with multi-year periods are taken into account, the farms with stable amount of arable surface are near 45%. This unexpected phenomenon halves suitable farm number for historical analysis, with consequence in terms of result representativeness (especially for ORG regime).
4.4.1.3 Farms and arable lands selected for analysis
By combining all previous mentioned aspects, it is possible to define two farm pools. The first one counts farms sampled 1 year and it has been used to individuate the most common rotational schemes (R.S. analysis). The second farm pool considers farms sampled more than once which are stable in terms of arable surface and regime for all period. In the figure 4.5 both farm
pools are described in terms of farm and arable land numbers.
Figure 4.5: in the histogram distribution and description of farms are reported separated by regime and wide of sample period. In the pie chart total amount of arable field with a rotational scheme is reported. Arable field are separated by regime (CON is circle external, ORG is inner circle) and farm description. The same legend, which is in the lower right side, describes both chart.
In the histogram it is possible to define a decrease of selected farms at increase of sample period wide. The major part of neglected farms record arable land variability, as previous analysis might suggest. In the pie chart ORG reports high percentage of arable lands selected for analysis. Indeed only 1 arable land on 3 is neglected. In CON this ratio rise at 1 neglected farm on 2. It suggests a high stability of ORG arable fields.