Will these dependencies remain regarding the intensity of the northern and southern solar magnetic fields?

On the graph above the cereal yield in Arab countries and in the USA is time-coordinated with the change of intensity of the solar magnetic field.

Let us enlarge the part of the graph, which is closer in time to the inversion of the magnetic field on the Sun in 2013.

In the USA, cereal yield is higher than in Arab countries when the northern magnetic pole is positive. With the sign change of the solar magnetic pole the graph of cereal yield growth in these countries diverges. For the cereals that grow in the USA the period when the northern magnetic pole has a positive charge is more favorable. Whereas for the cereals that grow in Arab countries the period when the northern magnetic pole has a negative charge is more favorable. But this is also connected with the Earth's rotational velocity.

Magnetic fields of the Sun and the Earth, as well as the velocity of its rotation, are all interconnected.

There is the graph to support this:

First, the Earth's magnetic field changes, after that – its rotational velocity. Although, at the scale of hundreds of years, this shift is not very noticeable.

Growth of plants is statistically related to the change of the Earth's magnetic field and with the change of its rotational velocity. Take into account that in different regions of the Earth the change dynamics of the magnetic field varies. Therefore, the shift to obtain a mapping between the graphs of the Earth's rotational velocity and the magnetic field intensity might be different in time.

The difference in cereal growth in the United States and Arab countries is higher at the greater difference in the intensity of the southern and northern solar magnetic fields.

Intensity of the solar magnetic pole is related to intensity of the Earth's magnetic pole. This relationship can be understood by analyzing the graph of Ukrainian scientists (V.D. Rusov, et al., 2011).

There is a relationship, a correspondence, but it is shifted in time.

What relationship is there between the cereal yield in the world and the intensity of the Earth's magnetic field? To learn this, let us take the data of space monitoring of the magnetic field intensity in various regions of the Earth.

Swarm reveals Earth’s changing magnetism, ESA, 19 June 2014, http://www.esa.int/Our_Activities/Observing_the_Earth/Swarm/Swarm_reveals_Earth_s_changing_magnetism

We will also present a graph of the change in the Earth's rotational velocity on the day when the data of its magnetic field were obtained.

It can be seen that the intensity of the magnetic field over North America is higher than over Arab countries. Then maybe this is the reason why we have a difference in cereal growth rates?

We will recheck this by comparing cereal growth in the world (matches cereal growth in the USA) with the growth in Argentina and Brazil where the magnetic field intensity is much lower.

Let us compare it with cereal yield in the USA.

Yes, the trends of yield growth by years are relatively opposite. Although growth prevails in all countries. And correlation between these data is positive. Whereas each year fluctuations, deviations from mean values, anomalies are relatively opposite.

The greatest differences in fluctuation rates occur in the late 80s, early 90s. The smallest differences occur in 1961 and 2013. 2013 is the time of polarity reversal of the solar magnetic field. This process is prolonged, it takes more than a year. But exactly in 2013 there were the greatest changes of the solar magnetic fields on its poles. The North Pole became positive. These years, there is the smallest difference in cereals growth between the USA and Arab countries. According to our data, in 2013 the difference in EEG frequencies of the subjects also decreased. GDP growth rates of various countries became less variable than they were before.

How did trees usually grow in Argentina, Brazil and the USA?

The trees have relatively opposite indicators, the same as in the case of cereals. At the same time, one must take into account the difference in temperature and climate between these countries.

Let us compare these graphs with the Earth's rotational velocity.

There is the relationship between the tree growth rates and the Earth's rotational velocity: tree growth in Brazil is higher with at the slowdown of rotational velocity. In the USA trees grow better at the growth of the Earth's rotational velocity.