YIELDING AND PROFITABILITY OF THE PRODUCTION OF WINTER TRITICALE CULTIVATED AFTER POTATO FERTILIZED WITH INTERCROPS AND STRAW

Anna Płaza
Department of Agrotechnology, Faculty of Natural Science, Siedlce University of Natural Sciences and Humanities, Poland

ABSTRACT

The study performed over 1999-2003 aimed at determining the yielding of winter triticale cultivated after table potato fertilized with intercrop biomass and straw. The study examined two factors: I – potato fertilization with intercrops (white clover, Italian ryegrass, oil radish, oil radish – mulch and control); II – potato fertilization with straw (split-block without straw, split-block with straw). The fertilizing value of white clover may be enhanced with the application of straw enriching soil in organic matter and working as a protection against nutrients leaching, nitrogen in particular, which results in the highest potato tuber yield. The most favorable after-effect on winter triticale yielding was recorded for potato fertilized with Italian ryegrass with straw. The application of intercrops, and intercrops with straw under winter triticale forecrop, resulted not only in the direct production costs increase but also in the growth of production value and direct surplus. The best production and economic results were recorded for winter triticale cultivated after potato fertilized with Italian ryegrass with straw.

Key words: after-effect, intercrop, straw, winter triticale, yield, economic evaluation.

INTRODUCTION

Under today’s economic conditions of Polish agriculture, the only method to maintain soils fertility appears to be a common cultivation of intercrops for green manure [1,6,7,9,16]. Intercrops do not only produce biomass but they also constitute a certain sorbent preventing nutrients leaching into deeper soil layers and ground-waters, which proves to be a significant factor for agricultural environment protection [11,13]. Intercrops cultivation performs also a phytosanitary function, frequently increasing cultivated crop yields. Intercrops constitute the source of biomass and macroelements not only for the plants cultivated directly after their application but also for the successive crops [4,7,9]. Straw left in the field after grain crops harvest, applied in combination with intercrops, may provide an alternative source of organic matter [9,12]. In sustainable farming, it is recommended to plant potatoes after intercrops and straw, to be subsequently followed by winter crops limiting nutrients leaching, nitrogen in particular. Winter triticale responding to cultivation in favorable stands with considerable yield increases is a valuable species.

The contemporary agricultural literature offers few experimental data defining the reaction of winter titicale to the after-effect of intercrops and straw. The present working hypothesis assumes that potato cultivated after various intercrops and straw will produce a different effect on yielding and profitability of winter triticale cultivation. The study performed aimed at evaluating the yielding of winter triticale cultivated after potato fertilized with intercrops biomass with straw.

MATERIAL AND METHODS

The field experiment was carried out over 1999-2003 at the Zawady Agricultural Experiment Station of the University of Podlasie in Siedlce on a very good rye complex soil of neutral pH and an average content of phosphorus, potassium and magnesium. The humus content was 1.39%. The experiment was set up in a split-block design, in three replications, on plots of 15 m² harvest area.

The study examined two factors:

1. Potato fertilization with intercrops:

• control (without fertilization with intercrops),

• undersown intercrops: white clover (18 kg·ha^-1), Italian ryegrass (30 kg·ha^-1),

• stubble intercrops – biomass ploughed-in in autumn: oil radish (30 kg·ha^-1),

• tubble intercrops – biomass left in the field as mulch until spring: oil radish (30 kg·ha^-1).

2. Potato fertilization with straw:

• split-block without straw,

• split-block with straw.

White clover and Italian ryegrass intercrops were undersown in spring barley cultivated for grain. Oil radish grown in stubble intercrops, however, was sown after spring barley harvest. The straw yield on each plot was determined after harvest and amounted to 4.3 t·ha^-1. Crushed straw was left in the filed or straw was taken away from the field. In all the plots, except for the one with white clover, a supplementary nitrogen dose of 7 kg per 1 ton of straw was applied. In autumn, the fresh matter yields of intercrops, including the root matter rinsed out from 30 cm soil layer, were determined on 1 m² of each plot. The mean fresh matter yield of intercrop amounted to: for white clover – 23.7 t·ha^-1, for Italian ryegrass – 33.4 t·ha^-1, and for oil radish – 29.8 t·ha^-1. Subsequently, the pre-winter 30 cm deep ploughing followed, except for the plots with oil radish which was left as mulch until spring.

In the first year after the application of organic fertilization, table potatoes of Rywal cultivar were cultivated, and in the following year, Tornado winter triticale cultivar was grown. The yield of fresh tubers was determined on each plot. After potato harvest, phosphorus (26.4 kg of P) and potassium (58.1 kg of K per 1 ha) fertilizers were applied. 220 kg·ha^-1of winter triticale grains were sown in the third decade of September. In spring, when the vegetation period started, the plantation was harrowed and fertilized with nitrogen (40 kg N·ha^-1). The second nitrogen dose (30 kg N·ha^-1) was applied at the shooting phase of triticale development.

Directly before harvest, on 1 m² of each plot ears were counted and sampled to determine the number of grains per ear and 1000 grain weight. The grain yield at 13% moisture content, and straw yield were determined. Based on prices valid in 2003, there was made the economic evaluation of winter triticale cultivated in the second year after the application of intercrops and straw. The costs of fertilization with intercrops and straw were divided into equal shares of 50% per year of the two year-period. The organic fertilizers examined differentiated the direct production costs. Straw value was determined with the comparative method, based on mineral components content, whereas green fertilizers value was calculated based on the costs of sowing material, mineral fertilizers and tillage practices. Other elements of winter triticale cultivation technology direct costs remained the same for all the fertilizing combinations, including material costs (sowing seeds, mineral fertilizers and pesticides) and human and mechanical labor expenditures estimated based on the technology applied in the experiment and labor consumption of individual practices in the production conditions at the Zawady Agricultural Experiment Station valid in 2003. Moreover, the production value and the direct surplus were calculated. The results obtained were verified with the analysis of variance for split-block design and with the Tuckey test at α = 0.05.

RESULTS AND DISCUSSION

The fresh potato tuber yield was significantly modified by the experimental factors and their interactions (Fig. 1). Of all the intercrops, the highest fertilizing value was obtained for white clover. Batalin et al. [1] also report on the highest potato tuber yield after the undersown red clover ploughing-in, which could be due to favorable chemical composition of papilionaceous plants and their high nitrogen content. Papilionaceous plants biomass mineralizes fast and provides the greatest amount of nutrients for the plants cultivated afterwards. In the present research, as in those reported by Gutmański et al. [4], oil radish ploughed-in in autumn, demonstrated a considerably lower after-effect than undersown white clover, which is a result of lower nutrient content in non-papilionaceous plants, particularly nitrogen content, which decreases their fertilizing value.

For fertilizing potato, stubble intercrops may be also applied as mulch. In the present research, oil radish left in the field as mulch until spring, demonstrated lower fertilizing value than when ploughed-in in autumn, probably because intercrops left as mulch slow down the mineralization process of organic matter, and thus provides the plant sown in spring with less nutrients [2]. In the present experiment, Italian ryegrass demonstrated the lowest fertilizing value of all the intercrops tested, however, also in this case, the potato tuber yield was 14.8% higher than the control.

The other factor significantly modifying the yield of potato tuber fresh yield was fertilization with straw where the yield was, on average, 7.3% higher than without straw. The interaction of the factors examined shows that the highest yield of potato tuber was obtained when fertilized with white clover and straw, which must have been due to high nitrogen loss during decomposition of papilionaceous plant biomass. Depending on soil temperature, moisture and decomposition time, nitrogen loss may account for up to 50%. To prevent it, a material rich in carbon, e.g. straw, should be added to the decomposing matter of papilionaceous plants to increase the C : N ratio [7]. What needs to be emphasized in the present research is that potato fertilized with oil radish as mulch with straw increased potato tuber yield as compared with fertilization with oil radish as mulch, only. The yield did not differ significantly from the one where potato was fertilized with oil radish ploughed-in in autumn in combination with straw or without straw because the application of straw in combination with oil radish as mulch enhances organic substance mineralization. The lowest potato tuber yield, however, was obtained without fertilization with intercrops.

The statistical analysis revealed a significant after-effect of fertilization with intercrops and straw, and of their interaction on the winter triticale yield (Fig. 2). The highest grain yield was recorded when winter triticale was cultivated in the second year after potato fertilized with Italian ryegrass. In the reports by Miczyński and Siwicki [7] and Batalin et al. [1], however, the highest increase in the successive crop grain yield was obtained for green manure of red clover or its combination with alfalfa. What needs to be considered, though, is the fact that the authors did not examine green grass manure. In the present research, white clover showed an after-effect significantly lower than that of Italian ryegrass probably because papilionaceous plants ploughed-in for green manure, due to a narrow C : N ratio, mineralize in soil faster [8]. Therefore, the nutrients released are mainly used by the plant cultivated directly after papilionaceous plants and, to a lower degree, by the successive crop. In the experiment performed, the after-effect of oil radish ploughed-in in autumn did not differ significantly from the after-effect of white clover. However, oil radish applied as mulch under potato demonstrated a significantly lower after-effect than white clover. Similarly, in the research reported by Małecka [6], white mustard applied as mulch showed a significantly lower after-effect on winter triticale yields than that of the combination of oat with pea. In the present research, potato fertilization with straw, particularly when it was applied in combination with Italian ryegrass, also demonstrated a favorable after-effect on winter triticale grain yield. Straw, the material rich in carbon, applied with a non-papilionaceous plant slows down the mineralization process of the ploughed-in biomass. Under such conditions, nutrients are less effectively utilized by potato cultivated in the first year and much better by the successive crop. Such favorable after-effect of supplementary biomass entered into soil is also emphasized by other authors [1,11,12,15,16].

The winter triticale grain yield is primarily dependent on the yield structure components (the number of ears, the number of grains per ear and 1000 grain weight) significantly affected by the experimental factors and their interactions (Tables 1, 2, 3). The best after-effect on the discussed winter triticale grain yield characteristics was recorded for Italian ryegrass. Prior to the harvest of winter triticale cultivated after potato fertilized with white clover, oil radish, and oil radish mulch, the number of ears did not differ significantly, though it was significantly lower than that obtained when potato was fertilized with Italian ryegrass. The number of grains per ear and 1000 grain weight of winter triticale cultivated in the second year after Italian ryegrass and white clover were significantly higher than when triticale was cultivated after oil radish ploughed-in in autumn and left as mulch until spring. The research by Wozniak [17] also shows a favorable after-effect of undersown intercrops on the grain yield structure components. Małecka [6] demonstrated that the number of ears prior to the harvest, and 1000 grain weight of winter triticale cultivated in the second year after the oat and pea mixture mulch and after white mustard, were significantly higher than those on the control, without intercrops. Also in the present research the parameters determining the grain yield structure of winter triticale cultivated in the second year after the application of intercrops were significantly higher than those on the control. Similarly to reports by Puła and Łabza [10], fertilization with straw produced a significant increase in the number of ears, the number of grains per ear, and 1000 grain weight, as compared to the control. Fertilization with Italian ryegrass in combination with straw, demonstrated the best effect on winter triticale grain yield components.

The winter triticale straw yield was significantly affected by potato fertilization with intercrops and straw as well as by their interaction (Fig. 3). Fertilization with intercrops increased the triticale straw yield by an average of 22.7% as compared with the control. The significantly highest winter triticale straw yield was obtained when forecrop was fertilized with Italian ryegrass. Also in the research by Siuta [12] and Małecka [6], organic fertilizers increased the successive crop straw yield. In the present research, fertilization with straw increased the winter triticale straw yield (by an average of 12.1%) as compared with the straw yield noted on the plots where straw was not applied under forecrop. The interaction of the factors examined shows that the highest winter triticale straw yield was harvested from the plots where potato was fertilized with Italian ryegrass with straw. The research by Miczyński and Siwicki [7] and Płaza et al. [9] revealed that undersown intercrops ploughed-in with a total of half of the dose of manure or straw, as compared with fertilization with undersown intercrops only, increase the successive crop straw yield. It results from the fact that intercrops applied in combination with manure or straw provide soil with a greater amount of biomass and macroelements to be utilized by plants in the crop rotation.

The income level, that is, the commercial production value, is determined by two factors, i.e. the yield level and market prices [5]. In the present research, the winter triticale production value was significantly differentiated by the interaction of potato fertilization with intercrops and straw (Fig. 4). The production value of winter triticale cultivated in the second year after potato fertilized with intercrops and intercrops with straw was significantly higher than the one noted in the control. The highest production value was recorded in the plots fertilized with Italian ryegrass with straw. Similarly, the production value in the other plots fertilized with intercrops and straw was higher than that noted in the plots fertilized only with intercrops, except for oil radish mulch. Potato fertilization with oil radish as mulch with straw resulted in a significant production value decrease, as compared with fertilization with oil radish as mulch without straw because winter triticale grain yield was also significantly lower. As reported by Harasim [5], the production value diminishes along with the decrease in the collected grain yield.

The level of direct production costs of winter triticale is mainly dependent on the applied cultivation technology [5,14]. The experimental factors interaction significantly modified the direct winter triticale production costs (Fig. 5). The significantly lowest direct production costs were noted for winter triticale cultivated in the control. Potato fertilization with intercrops, particularly with stubble intercrops, resulted in a significant increase in direct winter triticale production costs. Also the research by Batalin et al. [1] and Ceglarek and Płaza [3] show that undersown crops are the cheapest biomass source as they do not require additional inputs for cultivation and pre-sowing soil preparation, which is particularly troublesome in the stubble intercrops cultivation. The application of intercrops with straw resulted in a further direct production costs increase. The significantly lowest direct production costs were noted for winter triticale cultivated after potato fertilized with stubble intercrops ploughed-in in autumn or left until spring as mulch with straw.

Direct surplus, being the resultant of production value and direct production costs, is essential for the economic evaluation of winter triticale production. In the present research, the direct surplus was significantly modified by the interaction of experimental factors (Fig. 6). The application of intercrops and intercrops with straw under winter triticale forecrop, regardless of the direct production costs increase, resulted in a significant increase in direct surplus, as compared with its value recorded for the control, mainly due to the increase in grain yield. Harasim [5] also reported on the direct surplus value increase for crops cultivated on more favorable sites from which a higher grain yield was obtained. In the present experiment, potato fertilization with Italian ryegrass showed the most favorable effect on direct surplus. Fertilization with intercrops with straw resulted in a significant direct surplus level increase, as compared with fertilization with intercrops only, with the exception of oil radish, where the direct surplus level decrease by 424 PLN·ha^-1 was noted. It must have been due to direct production costs increase and the decrease in the grain yield which resulted in quicker oil radish mulch with straw mineralization and thus more favorable effect on potato yielding.

CONCLUSIONS

1. White clover fertilizing value may be enhanced with the application of straw enriching soil in organic substance as a protection against nutrients leaching, nitrogen in particular, which resulted altogether in the highest potato tuber yield.

2. The most favorable after-effect on winter triticale yielding and economic results was recorded for Italian ryegrass with straw under potato.

3. Due to a slower mineralization of ploughed-in non-papilionaceous plant biomass nutrients were less effectively utilized by potato cultivated directly after the plants applied and much better by the successive crop.

4. The application of intercrops and intercrops with straw under winter triticale forecrop resulted not only in the direct production costs increase but also in the growth of production value and the direct surplus level.

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Accepted for print: 23.11.2007

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