**3.1 Effect of balanced and unbalanced nutrition on crop production and soil fertility**

#### *3.1.1 Average agronomic and economic yields*

The balanced nutrition (N + P + K + Mg treatment) resulted in the highest average cereal unit yield of 5.4 t and an economic benefit of 1216 \$ha−1 (**Figure 1**). The average yield of 5.4 tha−1 is low because of the low-yielding varieties at the early decades of the trial and a low water holding capacity of the sandy soil at the site. Without fertilizer application, the yield was only 1.9 t and 469 \$ha−1. The application of P and K without N showed almost no increase in crop yield, 2.1 t and 404 \$ha−1. N fertilizer application but omitting P, K, and Mg resulted in a yield of 3.8 t and 831 \$ha−1. The yield declines due to omission of K + Mg, P + Mg, and Mg were respectively 18%, 9%, and 7% and the corresponding income loss were 315\$, 70\$ and 89\$ (**Figure 1**). Omitting K fertilizer leads to a higher yield reduction than omitting P fertilizer because of decreasing K supply from the soil (**Figure 2**). The yield and income loss due to the omission of P were rather small because of the high P content of the soil (**Figure 3**). Application of CAN with 4% MgO during 1958–2013 as a source of N resulted in low effect of omitting Mg fertilizer on crop yield. Application of only FYM decreased yield by 38% and 275\$ha−1 (**Figure 1**).

#### *3.1.2 Trend of average agronomic and economic yields*

Crop varieties improved during 62 years of the trial which can be seen in the yield increase over time in almost all treatments. The balanced nutrition (N + P + K + Mg treatment) resulted in the highest yield and income compared to nutrient omissions

*Effect of Balanced and Integrated Crop Nutrition on Sustainable Crop Production in a Classical… DOI: http://dx.doi.org/10.5772/intechopen.102682*

#### **Figure 1.**

*Effect of balanced nutrition, omitting nutrient, and FYM on average crop yields (n = 62 years); Grain yield with the same letters showed the insignificant difference.*

**Figure 2.**

*Effect of balanced nutrition, omitting nutrient, and FYM on soil K content in 0–30 cm depth.*

or FYM application without mineral fertilizer (**Figures 4** and **5**). Before 1980, the N fertilizer rate was insufficient to provide the N demand of potato and winter rye. The low N rate of 100 kgha−1 for potato and 60 kgha−1 for rye cultivation during1958–1980 (**Table 2**) and reduction of potato yield by nematodes infection in 1973–1982 resulted in decreasing yields during 1968–1980. Since 1980, increasing N rate and cultivating nematode resistance potato reversed the trend of decreasing yields. Improvement of crop variety resulted in increasing yields and income in all treatments, however declining cereal prices during 1990–2003 (data not shown) resulted in decreasing crop economic yield during 1993–2003. Compared to the income at the initial phase (1958–1963), the balanced nutrition increased crop income by 1981 \$ha−1 at the final (2014–2020) time interval (**Figure 5**).
