Agriculture in the Sahel faces many problems, such as soil depletion, which leads to low crop productivity and remains the most alarming threat [1] [2] . Located in the heart of the Sahel, Niger has a relatively undiversified economy that is largely dependent on agriculture. Like in other Sahelian countries, land degradation in Niger results in a decrease in soil fertility and low agricultural production, although the fact that agriculture is the main economic activity in the country, employing nearly 80% of the rural population [3] . This drop in productivity concerns several crops, including maize (Zea mays L.)

Maize is a cereal plant of the Poaceae family, producing grains and haulms widely used in sub-Saharan Africa [4] . It is an annual plant with almost no tillering [5] cultivated worldwide on more than 130 million hectares, with an estimated yield of 5.71 tonnes/ha in 2022 [6] . This yield is estimated at 2.22 tonnes/ha in Africa and 678 kg/ha in Niger [6] . In sub-Saharan Africa, maize grains are the basis for human food and also serve as raw material in several industries, and the residues are used for animal feed [7] . The maize plant plays an essential role in food security in Niger.

In Niger, corn is consumed grilled or after being transformed into flour to make dough or local couscous [8] . The deficit of agricultural products during the 2023 campaign led in 2024 to a steep rise in corn prices in sub-Saharan Africa in general and in Niger in particular [9] . According to the same authors, the kg of corn, which in previous years was between 100 FCFA and 150 FCFA, reached nearly 400 FCFA in 2024. Consequently, it is essential to create the conditions to increase the production of this commodity in sub-Saharan Africa in general and in Niger in particular. Furthermore, the use of fertilizers on improved varieties could contribute further to improving agricultural production in the context of advanced land degradation. Indeed, agricultural activity is only profitable with considerable nutrient inputs [10] . Researchers, namely Mukengere [11] , Useni [12] , Li [13] , Nyembo [14] , Koulibaly [15] , Coulibaly [16] , and Bakayoko [17] have shown that the contribution of organic manure (from chickens, cows), mineral fertilizers or the combination of the two fertilizers make it possible to improve the above-ground and below-ground biomass, the weight of grains per ear and the grain yield of corn.

However, beyond 1100 kg/ha of mineral fertilizers, corn grain yield decreases [18] . In addition, the timing of basal and maintenance fertilization can improve corncob weight [19] . The uncontrolled use of all these fertilizers can have negative repercussions on the environment and human health; hence, it is important to know when, in what form, and in what quantity to provide fertilizing elements [20] - [22] .

Today, few studies have been conducted in the Zinder region on the development of appropriate maize cultivation techniques to boost its productivity. Thus, to promote and popularize its cultivation in rural areas, this study aims at finding the best fertilizer to improve the productivity of the “Maka” maize variety in the Zinder region in Niger Republic.

The result of the variance analysis shows that fertilizers significantly affect most of the agronomic traits studied. Comparing the mean values, all treatments gave a higher result than the control treatment (T0, without fertilizer). This result confirms that of [26] , who observed differences in the durations of the vegetative and reproductive phases for four types of fertilizer. It emerges from this experiment that agronomic parameters such as male and female flowering and maturity studied at the level of composted poultry manure (T1) gave the best results for precocity. In addition, the best yield in dry corn cobs was obtained with treatment T1, with a yield greater than 7 tons per hectare. Treatment T1 and T5, respectively made it possible to obtain 4.8 and 4.2 times the yield obtained by the control. The same observation was made by [26] , who shows that organic manure based on chicken droppings improves corn yield compared to the control treatment. In addition, the combination of composted cow dung with NPK made it possible to obtain 4.2 times the yield obtained with the control treatment. This result confirms that of [11] , who also shows that the combination of organic and mineral fertilizers creates the best production conditions.

The results show that vegetative growth parameters such as plant height, stem collar diameter and number of leaves, leaf length and width at 35th DAS, 50th DAS, and maturity have different values between treatments and gave greater growth to treatment T1. This finding could be explained by the availability of mineral elements, including nitrogen, phosphorus, and potassium, in organic fertilizers based on poultry droppings for crop growth and development [27] . These results corroborate those of [22] , who show that treatments based on poultry droppings have significant repeated and residual effects on soil chemical parameters and that repeated application of poultry droppings still induces significant differences, including the highest N, P, and K contents. Also, plots treated with mineral manures or in combination with organic fertilizer gave a yield significantly different from unfertilized plots. This is due to the fact that the major nutrients in mineral fertilizers are substances that are readily assimilated by the plant. Kiari [28] notes that in the Maradi and Dosso regions, the use of NPK in sorrel cultivation favorably increased the leaf and grain yield of the latter.

Comparison of the mean stem diameter value showed that the mean values at maturity slightly decreased compared to those at the 35th and 50th DAS. This has already been reported by [26] in their study on “The effect of four types of fertilizers on the growth and productivity of two maize genotypes”, whereby they found that the mean values of collar diameter of plants treated with any fertilizer remain statistically equivalent from 85th to 92nd DAS.

As for the vegetative parameters, the contribution of poultry manures with or without the addition of mineral fertilizers significantly influenced all the yield parameters. The number of ears per plant, the number of grain rows per ear, the weight of grains per ear, the weight of 100 grains, and the grain yield were significantly affected by the contribution of fertilizers. The highest averages in number of ears, the weight of ears, and the weight of 100 grains were obtained with the treatment in composted poultry manure T1, followed by T5, which is a combination of cow dung plus NPK. These results could be due to the fact that the phosphorus (P) contained in these manures promotes fertilization, fruiting, and grain formation. Similar results were reported by [29] , according to which the contributions of composted poultry manure and NPK during the rainy and dry seasons on the cultivation of three okra varieties had positive effects on the growth and the production variables of the plants.

The principal component analysis carried out on the agronomic and morphological characteristics shows that treatment T1, followed by treatment T5 of group 3 are clearly far from the control treatment T0. This analysis also confirms that treatment T1 is clearly the best compared to the others. This result corroborates that of [26] , which shows that organic manure based on chicken droppings improves corn productivity compared to the control treatment.

The results of the study have shown that the treatment with composted poultry manure (T1) increases corn production. This treatment is the best for corn production. In addition, the combination of composted cow dung mixed with composted poultry manure (T5) and the combination of composted cow dung mixed with NPK (T3) also made it possible to obtain good yields of dry corn cobs. Finally, it appears from the study that the three treatments, including composted poultry manure (T1), the combination of composted cow dung with composted poultry manure (T5), and the combination of composted cow dung mixed with NPK (T3), are recommended to farmers in order to improve corn production and reduce environmental pollution following the use of mineral fertilizers.